diff --git a/build.gradle b/build.gradle
index f795a85a0aa9..cb0a04a3ab89 100644
--- a/build.gradle
+++ b/build.gradle
@@ -125,7 +125,7 @@ allprojects {
         buildId = getBuildId()
 
         buildToolsVersion = mozconfig.substs.ANDROID_BUILD_TOOLS_VERSION
-        compileSdkVersion = tryInt(mozconfig.substs.ANDROID_COMPILE_SDK)
+        compileSdkVersion = tryInt(mozconfig.substs.ANDROID_TARGET_SDK)
         targetSdkVersion = tryInt(mozconfig.substs.ANDROID_TARGET_SDK)
         minSdkVersion = tryInt(mozconfig.substs.MOZ_ANDROID_MIN_SDK_VERSION)
         manifestPlaceholders = [
diff --git a/build/moz.configure/android-sdk.configure b/build/moz.configure/android-sdk.configure
index 6df8c78f7790..7607ed2135b8 100644
--- a/build/moz.configure/android-sdk.configure
+++ b/build/moz.configure/android-sdk.configure
@@ -58,8 +58,7 @@ def android_sdk_version():
     # If you think you can't handle the whole set of changes, please reach out to the Release
     # Engineering team.
     return namespace(
-        build_tools_version="35.0.0",
-        compile_sdk_version="35",
+        build_tools_version="34.0.0",
         target_sdk_version="34",
         min_sdk_version="21",
     )
@@ -156,4 +155,3 @@ set_config("ANDROID_SDK_ROOT", android_sdk_root)
 
 set_config("ANDROID_BUILD_TOOLS_VERSION", android_sdk_version.build_tools_version)
 set_config("ANDROID_TARGET_SDK", android_sdk_version.target_sdk_version)
-set_config("ANDROID_COMPILE_SDK", android_sdk_version.compile_sdk_version)
diff --git a/mobile/android/android-components/.config.yml b/mobile/android/android-components/.config.yml
index d59aaa2e0d05..045cdf97402f 100644
--- a/mobile/android/android-components/.config.yml
+++ b/mobile/android/android-components/.config.yml
@@ -3,6 +3,6 @@ componentsGroupId: "org.mozilla.components"
 
 # Synchronized build configuration for all modules
 jvmTargetCompatibility: 17
-compileSdkVersion: 35
+compileSdkVersion: 34
 minSdkVersion: 21
 targetSdkVersion: 34
diff --git a/mobile/android/android-components/components/browser/engine-system/src/main/java/mozilla/components/browser/engine/system/SystemEngineSession.kt b/mobile/android/android-components/components/browser/engine-system/src/main/java/mozilla/components/browser/engine/system/SystemEngineSession.kt
index 1078a678ce0b..aaf2ec16342a 100644
--- a/mobile/android/android-components/components/browser/engine-system/src/main/java/mozilla/components/browser/engine/system/SystemEngineSession.kt
+++ b/mobile/android/android-components/components/browser/engine-system/src/main/java/mozilla/components/browser/engine/system/SystemEngineSession.kt
@@ -282,6 +282,7 @@ class SystemEngineSession(
             // Explicitly set global defaults.
 
             cacheMode = LOAD_NO_CACHE
+            databaseEnabled = false
 
             setDeprecatedWebSettings(this)
 
@@ -304,8 +305,6 @@ class SystemEngineSession(
         webSettings.saveFormData = false
         // Deprecated in API18.
         webSettings.savePassword = false
-        // Deprecated in API35; default value is false.
-        webSettings.databaseEnabled = false
     }
 
     private fun setUseWideViewPort(settings: WebSettings, useWideViewPort: Boolean?) {
diff --git a/mobile/android/android-components/components/browser/icons/src/main/java/mozilla/components/browser/icons/BrowserIcons.kt b/mobile/android/android-components/components/browser/icons/src/main/java/mozilla/components/browser/icons/BrowserIcons.kt
index 1fe889fed3fd..fe44cfc6be1a 100644
--- a/mobile/android/android-components/components/browser/icons/src/main/java/mozilla/components/browser/icons/BrowserIcons.kt
+++ b/mobile/android/android-components/components/browser/icons/src/main/java/mozilla/components/browser/icons/BrowserIcons.kt
@@ -341,8 +341,6 @@ class BrowserIcons constructor(
         sharedMemoryCache.clear()
     }
 
-    @Suppress("DEPRECATION") // Apps are not notified of these levels since API level 34.
-    // See https://bugzilla.mozilla.org/show_bug.cgi?id=1909473
     override fun onTrimMemory(level: Int) {
         val shouldClearMemoryCache = when (level) {
             // Foreground: The device is running much lower on memory. The app is running and not killable, but the
diff --git a/mobile/android/android-components/components/browser/state/src/main/java/mozilla/components/browser/state/engine/middleware/TrimMemoryMiddleware.kt b/mobile/android/android-components/components/browser/state/src/main/java/mozilla/components/browser/state/engine/middleware/TrimMemoryMiddleware.kt
index 74f212c42384..23c49d9262b9 100644
--- a/mobile/android/android-components/components/browser/state/src/main/java/mozilla/components/browser/state/engine/middleware/TrimMemoryMiddleware.kt
+++ b/mobile/android/android-components/components/browser/state/src/main/java/mozilla/components/browser/state/engine/middleware/TrimMemoryMiddleware.kt
@@ -77,8 +77,6 @@ internal class TrimMemoryMiddleware : Middleware<BrowserState, BrowserAction> {
     }
 }
 
-@Suppress("DEPRECATION") // Apps are not notified of these levels since API level 34.
-// See https://bugzilla.mozilla.org/show_bug.cgi?id=1909473
 private fun shouldCloseEngineSessions(level: Int): Boolean {
     return when (level) {
         // Foreground: The device is running extremely low on memory. The app is not yet considered a killable
diff --git a/mobile/android/android-components/components/browser/state/src/test/java/mozilla/components/browser/state/engine/middleware/TrimMemoryMiddlewareTest.kt b/mobile/android/android-components/components/browser/state/src/test/java/mozilla/components/browser/state/engine/middleware/TrimMemoryMiddlewareTest.kt
index 271aca41427d..f0ba85d952b5 100644
--- a/mobile/android/android-components/components/browser/state/src/test/java/mozilla/components/browser/state/engine/middleware/TrimMemoryMiddlewareTest.kt
+++ b/mobile/android/android-components/components/browser/state/src/test/java/mozilla/components/browser/state/engine/middleware/TrimMemoryMiddlewareTest.kt
@@ -192,8 +192,6 @@ class TrimMemoryMiddlewareTest {
 
     @Test
     fun `TrimMemoryMiddleware - TRIM_MEMORY_RUNNING_CRITICAL`() {
-        @Suppress("DEPRECATION") // Apps are not notified of these levels since API level 34.
-        // See https://bugzilla.mozilla.org/show_bug.cgi?id=1909473
         store.dispatch(
             SystemAction.LowMemoryAction(
                 level = ComponentCallbacks2.TRIM_MEMORY_RUNNING_CRITICAL,
diff --git a/mobile/android/android-components/components/feature/autofill/src/main/java/mozilla/components/feature/autofill/response/dataset/LoginDatasetBuilder.kt b/mobile/android/android-components/components/feature/autofill/src/main/java/mozilla/components/feature/autofill/response/dataset/LoginDatasetBuilder.kt
index 4c55c0174adf..24fac38825fc 100644
--- a/mobile/android/android-components/components/feature/autofill/src/main/java/mozilla/components/feature/autofill/response/dataset/LoginDatasetBuilder.kt
+++ b/mobile/android/android-components/components/feature/autofill/src/main/java/mozilla/components/feature/autofill/response/dataset/LoginDatasetBuilder.kt
@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-@file:Suppress("DEPRECATION")
-
 package mozilla.components.feature.autofill.response.dataset
 
 import android.annotation.SuppressLint
diff --git a/mobile/android/android-components/components/feature/customtabs/src/test/java/mozilla/components/feature/customtabs/CustomTabsToolbarFeatureTest.kt b/mobile/android/android-components/components/feature/customtabs/src/test/java/mozilla/components/feature/customtabs/CustomTabsToolbarFeatureTest.kt
index 607389ccd054..5f4384f2494f 100644
--- a/mobile/android/android-components/components/feature/customtabs/src/test/java/mozilla/components/feature/customtabs/CustomTabsToolbarFeatureTest.kt
+++ b/mobile/android/android-components/components/feature/customtabs/src/test/java/mozilla/components/feature/customtabs/CustomTabsToolbarFeatureTest.kt
@@ -126,7 +126,6 @@ class CustomTabsToolbarFeatureTest {
         assertFalse(toolbar.display.onUrlClicked.invoke())
     }
 
-    @Suppress("DEPRECATION")
     @Test
     @Config(sdk = [28])
     fun `initialize updates toolbar, window and text color on SDK 28`() {
@@ -167,7 +166,6 @@ class CustomTabsToolbarFeatureTest {
         assertEquals(Color.WHITE, toolbar.display.colors.text)
     }
 
-    @Suppress("DEPRECATION")
     @Test
     fun `initialize updates toolbar, window and text color`() {
         val tab = createCustomTab(
diff --git a/mobile/android/android-components/components/service/digitalassetlinks/src/main/java/mozilla/components/service/digitalassetlinks/AndroidAssetFinder.kt b/mobile/android/android-components/components/service/digitalassetlinks/src/main/java/mozilla/components/service/digitalassetlinks/AndroidAssetFinder.kt
index cd23691415f3..bd4e497d3489 100644
--- a/mobile/android/android-components/components/service/digitalassetlinks/src/main/java/mozilla/components/service/digitalassetlinks/AndroidAssetFinder.kt
+++ b/mobile/android/android-components/components/service/digitalassetlinks/src/main/java/mozilla/components/service/digitalassetlinks/AndroidAssetFinder.kt
@@ -68,8 +68,8 @@ class AndroidAssetFinder {
     private fun PackageManager.getSignatures(packageName: String): Array<Signature> {
         val packageInfo = getPackageSignatureInfo(packageName) ?: return emptyArray()
 
-        val signatures = if (SDK_INT >= Build.VERSION_CODES.P) {
-            val signingInfo = packageInfo.signingInfo ?: return emptyArray()
+        return if (SDK_INT >= Build.VERSION_CODES.P) {
+            val signingInfo = packageInfo.signingInfo
             if (signingInfo.hasMultipleSigners()) {
                 signingInfo.apkContentsSigners
             } else {
@@ -82,10 +82,8 @@ class AndroidAssetFinder {
             }
         } else {
             @Suppress("Deprecation")
-            packageInfo.signatures ?: emptyArray()
+            packageInfo.signatures
         }
-
-        return signatures
     }
 
     @SuppressLint("PackageManagerGetSignatures")
diff --git a/mobile/android/android-components/components/support/ktx/src/main/java/mozilla/components/support/ktx/android/content/Context.kt b/mobile/android/android-components/components/support/ktx/src/main/java/mozilla/components/support/ktx/android/content/Context.kt
index d83a2c7b4003..03975201f8c7 100644
--- a/mobile/android/android-components/components/support/ktx/src/main/java/mozilla/components/support/ktx/android/content/Context.kt
+++ b/mobile/android/android-components/components/support/ktx/src/main/java/mozilla/components/support/ktx/android/content/Context.kt
@@ -24,7 +24,6 @@ import android.content.pm.PackageManager.PERMISSION_GRANTED
 import android.hardware.camera2.CameraManager
 import android.net.Uri
 import android.os.Build
-import android.os.Build.VERSION.SDK_INT
 import android.os.Process
 import android.provider.ContactsContract
 import android.view.accessibility.AccessibilityManager
@@ -46,10 +45,10 @@ import java.io.File
 
 /**
  * The (visible) version name of the application, as specified by the <manifest> tag's versionName
- * attribute. E.g. "2.0". Returns an empty string if versionName is null.
+ * attribute. E.g. "2.0".
  */
 val Context.appVersionName: String
-    get() = packageManager.getPackageInfoCompat(packageName, 0).versionName ?: ""
+    get() = packageManager.getPackageInfoCompat(packageName, 0).versionName
 
 /**
  * Returns the name (label) of the application or the package name as a fallback.
@@ -333,18 +332,6 @@ inline fun Context.runOnlyInMainProcess(block: () -> Unit) {
 fun Context.getColorFromAttr(@AttrRes attr: Int) =
     ContextCompat.getColor(this, theme.resolveAttribute(attr))
 
-/**
- * Returns the color int corresponding to the Android statusBarColor attribute.
- */
-@ColorInt
-fun Context.getStatusBarColor() =
-    if (SDK_INT < Build.VERSION_CODES.VANILLA_ICE_CREAM) {
-        @Suppress("DEPRECATION")
-        ContextCompat.getColor(this, theme.resolveAttribute(android.R.attr.statusBarColor))
-    } else {
-        null
-    }
-
 /**
  * Returns a tinted drawable for the given resource ID.
  * @param resId ID of the drawable to load.
diff --git a/mobile/android/android-components/components/support/ktx/src/main/java/mozilla/components/support/ktx/android/graphics/Bitmap.kt b/mobile/android/android-components/components/support/ktx/src/main/java/mozilla/components/support/ktx/android/graphics/Bitmap.kt
index e0c81c29aebd..bac132e64e1b 100644
--- a/mobile/android/android-components/components/support/ktx/src/main/java/mozilla/components/support/ktx/android/graphics/Bitmap.kt
+++ b/mobile/android/android-components/components/support/ktx/src/main/java/mozilla/components/support/ktx/android/graphics/Bitmap.kt
@@ -5,7 +5,6 @@
 package mozilla.components.support.ktx.android.graphics
 
 import android.graphics.Bitmap
-import android.graphics.Bitmap.Config
 import android.graphics.BitmapShader
 import android.graphics.Canvas
 import android.graphics.Paint
@@ -36,7 +35,7 @@ private const val BITMAP_COMPRESSION_QUALITY = 100
  * - Wrap your bitmap's ImageView with a layout that masks your view with rounded corners (e.g. CardView)
  */
 @CheckResult
-fun Bitmap.withRoundedCorners(cornerRadiusPx: Float, config: Config): Bitmap {
+fun Bitmap.withRoundedCorners(cornerRadiusPx: Float): Bitmap {
     val roundedBitmap = Bitmap.createBitmap(width, height, config)
     val canvas = Canvas(roundedBitmap)
     val paint = Paint().apply {
diff --git a/mobile/android/android-components/components/support/ktx/src/main/java/mozilla/components/support/ktx/android/view/Window.kt b/mobile/android/android-components/components/support/ktx/src/main/java/mozilla/components/support/ktx/android/view/Window.kt
index faf9c763786d..0e564cf6cf27 100644
--- a/mobile/android/android-components/components/support/ktx/src/main/java/mozilla/components/support/ktx/android/view/Window.kt
+++ b/mobile/android/android-components/components/support/ktx/src/main/java/mozilla/components/support/ktx/android/view/Window.kt
@@ -17,7 +17,7 @@ import mozilla.components.support.utils.ColorUtils.isDark
  */
 fun Window.setStatusBarTheme(@ColorInt color: Int) {
     createWindowInsetsController().isAppearanceLightStatusBars = !isDark(color)
-    setStatusBarColorCompat(color)
+    statusBarColor = color
 }
 
 /**
@@ -29,10 +29,13 @@ fun Window.setNavigationBarTheme(
     @ColorInt navBarDividerColor: Int? = null,
 ) {
     navBarColor?.let {
-        setNavigationBarColorCompat(it)
+        navigationBarColor = it
         createWindowInsetsController().isAppearanceLightNavigationBars = !isDark(it)
     }
-    setNavigationBarDividerColorCompat(navBarDividerColor)
+
+    if (SDK_INT >= Build.VERSION_CODES.P) {
+        navigationBarDividerColor = navBarDividerColor ?: 0
+    }
 }
 
 /**
@@ -41,39 +44,3 @@ fun Window.setNavigationBarTheme(
 fun Window.createWindowInsetsController(): WindowInsetsControllerCompat {
     return WindowInsetsControllerCompat(this, this.decorView)
 }
-
-/**
- * Sets the status bar color.
- *
- * @param color The color to set as the status bar color.
- */
-fun Window.setStatusBarColorCompat(@ColorInt color: Int) {
-    if (SDK_INT < Build.VERSION_CODES.VANILLA_ICE_CREAM) {
-        @Suppress("DEPRECATION")
-        statusBarColor = color
-    }
-}
-
-/**
- * Sets the navigation bar color.
- *
- * @param color The color to set as the navigation bar color.
- */
-fun Window.setNavigationBarColorCompat(@ColorInt color: Int) {
-    if (SDK_INT < Build.VERSION_CODES.VANILLA_ICE_CREAM) {
-        @Suppress("DEPRECATION")
-        navigationBarColor = color
-    }
-}
-
-/**
- * Sets the navigation bar divider color.
- *
- * @param color The color to set as the navigation bar divider color.
- */
-fun Window.setNavigationBarDividerColorCompat(@ColorInt color: Int?) {
-    if (SDK_INT >= Build.VERSION_CODES.P && SDK_INT < Build.VERSION_CODES.VANILLA_ICE_CREAM) {
-        @Suppress("DEPRECATION")
-        navigationBarDividerColor = color ?: 0
-    }
-}
diff --git a/mobile/android/android-components/components/support/ktx/src/test/java/mozilla/components/support/ktx/android/content/ContextTest.kt b/mobile/android/android-components/components/support/ktx/src/test/java/mozilla/components/support/ktx/android/content/ContextTest.kt
index 66d03d77df76..aa6782f4f5a1 100644
--- a/mobile/android/android-components/components/support/ktx/src/test/java/mozilla/components/support/ktx/android/content/ContextTest.kt
+++ b/mobile/android/android-components/components/support/ktx/src/test/java/mozilla/components/support/ktx/android/content/ContextTest.kt
@@ -18,8 +18,6 @@ import android.content.Intent.EXTRA_SUBJECT
 import android.content.Intent.EXTRA_TEXT
 import android.content.Intent.EXTRA_TITLE
 import android.content.Intent.FLAG_ACTIVITY_NEW_TASK
-import android.content.pm.PackageInfo
-import android.content.pm.PackageManager
 import android.content.pm.PackageManager.PERMISSION_GRANTED
 import android.hardware.camera2.CameraManager
 import android.net.Uri
@@ -29,7 +27,6 @@ import androidx.core.content.getSystemService
 import androidx.core.net.toUri
 import androidx.test.ext.junit.runners.AndroidJUnit4
 import mozilla.components.support.ktx.R
-import mozilla.components.support.test.any
 import mozilla.components.support.test.argumentCaptor
 import mozilla.components.support.test.fakes.android.FakeContext
 import mozilla.components.support.test.mock
@@ -42,11 +39,9 @@ import org.junit.Assert.assertTrue
 import org.junit.Before
 import org.junit.Test
 import org.junit.runner.RunWith
-import org.mockito.Mockito.anyString
 import org.mockito.Mockito.doReturn
 import org.mockito.Mockito.spy
 import org.mockito.Mockito.verify
-import org.mockito.Mockito.`when`
 import org.robolectric.Robolectric
 import org.robolectric.Shadows.shadowOf
 import org.robolectric.annotation.Config
@@ -292,44 +287,6 @@ class ContextTest {
         whenever(cameraManager.cameraIdList).thenThrow(AssertionError("Test"))
         assertFalse(context.hasCamera())
     }
-
-    @Test
-    fun `appVersionName returns proper value`() {
-        val context: Context = mock()
-        val packageManager: PackageManager = mock()
-        val packageInfo = PackageInfo().apply { versionName = "1.0.0" }
-
-        `when`(context.packageManager).thenReturn(packageManager)
-        `when`(context.packageName).thenReturn("org.mozilla.app")
-        `when`(
-            packageManager.getPackageInfo(
-                anyString(),
-                any<PackageManager.PackageInfoFlags>(),
-            ),
-        ).thenReturn(packageInfo)
-
-        val versionName = context.appVersionName
-        assertEquals("1.0.0", versionName)
-    }
-
-    @Test
-    fun `appVersionName returns empty string when versionName is null`() {
-        val context: Context = mock()
-        val packageManager: PackageManager = mock()
-        val packageInfo = PackageInfo().apply { versionName = null }
-
-        `when`(context.packageManager).thenReturn(packageManager)
-        `when`(context.packageName).thenReturn("org.mozilla.app")
-        `when`(
-            packageManager.getPackageInfo(
-                anyString(),
-                any<PackageManager.PackageInfoFlags>(),
-            ),
-        ).thenReturn(packageInfo)
-
-        val versionName = context.appVersionName
-        assertEquals("", versionName)
-    }
 }
 
 @Implements(FileProvider::class)
diff --git a/mobile/android/android-components/components/support/ktx/src/test/java/mozilla/components/support/ktx/android/graphics/BitmapKtTest.kt b/mobile/android/android-components/components/support/ktx/src/test/java/mozilla/components/support/ktx/android/graphics/BitmapKtTest.kt
index 7d0d8772283a..acd57c11943a 100644
--- a/mobile/android/android-components/components/support/ktx/src/test/java/mozilla/components/support/ktx/android/graphics/BitmapKtTest.kt
+++ b/mobile/android/android-components/components/support/ktx/src/test/java/mozilla/components/support/ktx/android/graphics/BitmapKtTest.kt
@@ -31,12 +31,11 @@ class BitmapKtTest {
     fun `WHEN withRoundedCorners is called THEN returned bitmap's corners should be transparent and center with color`() {
         val dimen = 200
         val fillColor = Color.RED
-        val config = Bitmap.Config.ARGB_8888
 
-        val bitmap = Bitmap.createBitmap(dimen, dimen, config).apply {
+        val bitmap = Bitmap.createBitmap(dimen, dimen, Bitmap.Config.ARGB_8888).apply {
             eraseColor(fillColor)
         }
-        val roundedBitmap = bitmap.withRoundedCorners(40f, config)
+        val roundedBitmap = bitmap.withRoundedCorners(40f)
 
         fun assertCornersAreTransparent() {
             val cornerLocations = listOf(0, dimen - 1)
diff --git a/mobile/android/android-components/components/support/ktx/src/test/java/mozilla/components/support/ktx/android/view/WindowTest.kt b/mobile/android/android-components/components/support/ktx/src/test/java/mozilla/components/support/ktx/android/view/WindowTest.kt
index cedeb8595440..24e49b9ce524 100644
--- a/mobile/android/android-components/components/support/ktx/src/test/java/mozilla/components/support/ktx/android/view/WindowTest.kt
+++ b/mobile/android/android-components/components/support/ktx/src/test/java/mozilla/components/support/ktx/android/view/WindowTest.kt
@@ -46,7 +46,6 @@ class WindowTest {
     @After
     fun teardown() = setStaticField(Build.VERSION::SDK_INT.javaField, 0)
 
-    @Suppress("DEPRECATION")
     @Test
     fun `GIVEN a color WHEN setStatusBarTheme THEN sets the status bar color`() {
         window.setStatusBarTheme(Color.BLUE)
@@ -65,7 +64,6 @@ class WindowTest {
     }
 
     @Test
-    @Suppress("DEPRECATION")
     fun `GIVEN Android 8 & has nav bar color WHEN setNavigationBarTheme THEN only the nav bar color is set`() {
         setStaticField(Build.VERSION::SDK_INT.javaField, Build.VERSION_CODES.O_MR1)
         window.setNavigationBarTheme(navBarColor = Color.MAGENTA)
@@ -87,7 +85,6 @@ class WindowTest {
     }
 
     @Test
-    @Suppress("DEPRECATION")
     fun `GIVEN Android 8 & all args WHEN setNavigationBarTheme THEN only the nav bar color is set`() {
         setStaticField(Build.VERSION::SDK_INT.javaField, Build.VERSION_CODES.O_MR1)
         window.setNavigationBarTheme(navBarColor = Color.MAGENTA, navBarDividerColor = Color.DKGRAY)
@@ -101,7 +98,6 @@ class WindowTest {
     }
 
     @Test
-    @Suppress("DEPRECATION")
     fun `GIVEN Android 9 & no args WHEN setNavigationBarTheme THEN the nav bar divider color is set to default`() {
         setStaticField(Build.VERSION::SDK_INT.javaField, Build.VERSION_CODES.P)
         window.setNavigationBarTheme()
@@ -111,7 +107,6 @@ class WindowTest {
     }
 
     @Test
-    @Suppress("DEPRECATION")
     fun `GIVEN Android 9 has nav bar color WHEN setNavigationBarTheme THEN the nav bar color is set & nav bar divider color set to default`() {
         setStaticField(Build.VERSION::SDK_INT.javaField, Build.VERSION_CODES.P)
         window.setNavigationBarTheme(navBarColor = Color.BLUE)
@@ -121,7 +116,6 @@ class WindowTest {
     }
 
     @Test
-    @Suppress("DEPRECATION")
     fun `GIVEN Android 9 has nav bar divider color WHEN setNavigationBarTheme THEN only the nav bar divider color is set`() {
         setStaticField(Build.VERSION::SDK_INT.javaField, Build.VERSION_CODES.P)
         window.setNavigationBarTheme(navBarDividerColor = Color.GREEN)
@@ -131,7 +125,6 @@ class WindowTest {
     }
 
     @Test
-    @Suppress("DEPRECATION")
     fun `GIVEN Android 9 & all args WHEN setNavigationBarTheme THEN the nav bar & nav bar divider colors are set`() {
         setStaticField(Build.VERSION::SDK_INT.javaField, Build.VERSION_CODES.P)
         window.setNavigationBarTheme(navBarColor = Color.YELLOW, navBarDividerColor = Color.CYAN)
diff --git a/mobile/android/android-components/docs/changelog.md b/mobile/android/android-components/docs/changelog.md
index 56562e3e3677..cb0038d0676c 100644
--- a/mobile/android/android-components/docs/changelog.md
+++ b/mobile/android/android-components/docs/changelog.md
@@ -5,8 +5,6 @@ permalink: /changelog/
 ---
 
 # 131.0 (In Development)
-* **All components**
-  * ⚠️Increased `compileSdkVersion` to 35 (Android 15)
 
 # 130.0
 
diff --git a/mobile/android/fenix/app/src/main/java/org/mozilla/fenix/theme/ThemeManager.kt b/mobile/android/fenix/app/src/main/java/org/mozilla/fenix/theme/ThemeManager.kt
index 74d87261decf..3ff4b2786493 100644
--- a/mobile/android/fenix/app/src/main/java/org/mozilla/fenix/theme/ThemeManager.kt
+++ b/mobile/android/fenix/app/src/main/java/org/mozilla/fenix/theme/ThemeManager.kt
@@ -18,10 +18,7 @@ import androidx.compose.runtime.Composable
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.res.colorResource
 import mozilla.components.support.ktx.android.content.getColorFromAttr
-import mozilla.components.support.ktx.android.content.getStatusBarColor
 import mozilla.components.support.ktx.android.view.createWindowInsetsController
-import mozilla.components.support.ktx.android.view.setNavigationBarColorCompat
-import mozilla.components.support.ktx.android.view.setStatusBarColorCompat
 import org.mozilla.fenix.HomeActivity
 import org.mozilla.fenix.R
 import org.mozilla.fenix.browser.browsingmode.BrowsingMode
@@ -90,10 +87,10 @@ abstract class ThemeManager(
 
         private fun updateLightSystemBars(window: Window, context: Context) {
             if (SDK_INT >= Build.VERSION_CODES.M) {
-                context.getStatusBarColor()?.let { window.setStatusBarColorCompat(it) }
+                window.statusBarColor = context.getColorFromAttr(android.R.attr.statusBarColor)
                 window.createWindowInsetsController().isAppearanceLightStatusBars = true
             } else {
-                window.setStatusBarColorCompat(Color.BLACK)
+                window.statusBarColor = Color.BLACK
             }
 
             if (SDK_INT >= Build.VERSION_CODES.O) {
@@ -116,7 +113,7 @@ abstract class ThemeManager(
         }
 
         private fun updateNavigationBar(window: Window, context: Context) {
-            window.setNavigationBarColorCompat(context.getColorFromAttr(R.attr.layer1))
+            window.navigationBarColor = context.getColorFromAttr(R.attr.layer1)
         }
     }
 }
diff --git a/mobile/android/fenix/app/src/test/java/org/mozilla/fenix/wifi/WifiConnectionMonitorTest.kt b/mobile/android/fenix/app/src/test/java/org/mozilla/fenix/wifi/WifiConnectionMonitorTest.kt
index f66b90b08765..7ac567d4bd26 100644
--- a/mobile/android/fenix/app/src/test/java/org/mozilla/fenix/wifi/WifiConnectionMonitorTest.kt
+++ b/mobile/android/fenix/app/src/test/java/org/mozilla/fenix/wifi/WifiConnectionMonitorTest.kt
@@ -18,7 +18,6 @@ import org.junit.Test
 import org.junit.runner.RunWith
 import org.mozilla.fenix.helpers.FenixRobolectricTestRunner
 import org.mozilla.fenix.utils.Settings
-import kotlin.collections.removeFirst as removeFirstKt
 
 @RunWith(FenixRobolectricTestRunner::class)
 class WifiConnectionMonitorTest {
@@ -180,7 +179,7 @@ class WifiConnectionMonitorTest {
             wifiConnectionMonitor.addOnWifiConnectedChangedListener {
                 // Altering callbacks while looping.
                 if (wifiConnectionMonitor.callbacks.isNotEmpty()) {
-                    wifiConnectionMonitor.callbacks.removeFirstKt()
+                    wifiConnectionMonitor.callbacks.removeFirst()
                 }
             }
 
diff --git a/mobile/android/focus-android/app/src/androidTest/java/org/mozilla/focus/activity/robots/SettingsMozillaMenuRobot.kt b/mobile/android/focus-android/app/src/androidTest/java/org/mozilla/focus/activity/robots/SettingsMozillaMenuRobot.kt
index 9d1aaf197207..c5ce1748eb8e 100644
--- a/mobile/android/focus-android/app/src/androidTest/java/org/mozilla/focus/activity/robots/SettingsMozillaMenuRobot.kt
+++ b/mobile/android/focus-android/app/src/androidTest/java/org/mozilla/focus/activity/robots/SettingsMozillaMenuRobot.kt
@@ -42,7 +42,7 @@ class SettingsMozillaMenuRobot {
     fun verifyVersionNumbers() {
         val context = InstrumentationRegistry.getInstrumentation().targetContext
         val packageInfo = context.packageManager.getPackageInfoCompat(context.packageName, 0)
-        val versionName = packageInfo.versionName ?: ""
+        val versionName = packageInfo.versionName
         val gvBuildId = org.mozilla.geckoview.BuildConfig.MOZ_APP_BUILDID
         val gvVersion = org.mozilla.geckoview.BuildConfig.MOZ_APP_VERSION
 
diff --git a/mobile/android/focus-android/app/src/main/java/org/mozilla/focus/activity/MainActivity.kt b/mobile/android/focus-android/app/src/main/java/org/mozilla/focus/activity/MainActivity.kt
index 55c17eb09fa1..4a70addc045d 100644
--- a/mobile/android/focus-android/app/src/main/java/org/mozilla/focus/activity/MainActivity.kt
+++ b/mobile/android/focus-android/app/src/main/java/org/mozilla/focus/activity/MainActivity.kt
@@ -28,11 +28,8 @@ import mozilla.components.feature.search.widget.BaseVoiceSearchActivity
 import mozilla.components.lib.auth.canUseBiometricFeature
 import mozilla.components.lib.crash.Crash
 import mozilla.components.support.base.feature.UserInteractionHandler
-import mozilla.components.support.ktx.android.content.getStatusBarColor
+import mozilla.components.support.ktx.android.content.getColorFromAttr
 import mozilla.components.support.ktx.android.view.createWindowInsetsController
-import mozilla.components.support.ktx.android.view.setNavigationBarColorCompat
-import mozilla.components.support.ktx.android.view.setNavigationBarDividerColorCompat
-import mozilla.components.support.ktx.android.view.setStatusBarColorCompat
 import mozilla.components.support.locale.LocaleAwareAppCompatActivity
 import mozilla.components.support.utils.SafeIntent
 import mozilla.components.support.utils.StatusBarUtils
@@ -110,7 +107,7 @@ open class MainActivity : LocaleAwareAppCompatActivity() {
         window.decorView.systemUiVisibility =
             View.SYSTEM_UI_FLAG_LAYOUT_STABLE or View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
 
-        window.setStatusBarColorCompat(ContextCompat.getColor(this, android.R.color.transparent))
+        window.statusBarColor = ContextCompat.getColor(this, android.R.color.transparent)
         when (resources.configuration.uiMode and Configuration.UI_MODE_NIGHT_MASK) {
             Configuration.UI_MODE_NIGHT_UNDEFINED, // We assume light here per Android doc's recommendation
             Configuration.UI_MODE_NIGHT_NO,
@@ -396,21 +393,20 @@ open class MainActivity : LocaleAwareAppCompatActivity() {
 
     private fun updateLightSystemBars() {
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
-            window.context.getStatusBarColor()?.let { window.setStatusBarColorCompat(it) }
+            window.statusBarColor = getColorFromAttr(android.R.attr.statusBarColor)
             window.createWindowInsetsController().isAppearanceLightStatusBars = true
         } else {
-            window.setStatusBarColorCompat(Color.BLACK)
+            window.statusBarColor = Color.BLACK
         }
 
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
             // API level can display handle light navigation bar color
             window.createWindowInsetsController().isAppearanceLightNavigationBars = true
-            window.setNavigationBarColorCompat(ContextCompat.getColor(this, android.R.color.transparent))
+            window.navigationBarColor = ContextCompat.getColor(this, android.R.color.transparent)
 
             if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.P) {
-                window.setNavigationBarDividerColorCompat(
-                    ContextCompat.getColor(this, android.R.color.transparent),
-                )
+                window.navigationBarDividerColor =
+                    ContextCompat.getColor(this, android.R.color.transparent)
             }
         }
     }
diff --git a/mobile/android/focus-android/app/src/main/java/org/mozilla/focus/utils/SupportUtils.kt b/mobile/android/focus-android/app/src/main/java/org/mozilla/focus/utils/SupportUtils.kt
index 897ca52cb9a0..dbaf7d84aae1 100644
--- a/mobile/android/focus-android/app/src/main/java/org/mozilla/focus/utils/SupportUtils.kt
+++ b/mobile/android/focus-android/app/src/main/java/org/mozilla/focus/utils/SupportUtils.kt
@@ -85,11 +85,11 @@ object SupportUtils {
     }
 
     /**
-     * Returns the version name of this package or an empty string if versionName is null.
+     * Returns the version name of this package.
      */
     fun getAppVersion(context: Context): String {
         try {
-            return context.packageManager.getPackageInfoCompat(context.packageName, 0).versionName ?: ""
+            return context.packageManager.getPackageInfoCompat(context.packageName, 0).versionName
         } catch (e: PackageManager.NameNotFoundException) {
             // This should be impossible - we should always be able to get information about ourselves:
             throw IllegalStateException("Unable find package details for Focus", e)
diff --git a/mobile/android/focus-android/app/src/test/java/org/mozilla/focus/utils/SupportUtilsTest.kt b/mobile/android/focus-android/app/src/test/java/org/mozilla/focus/utils/SupportUtilsTest.kt
index 4c1aac014828..fe55d8d4f87c 100644
--- a/mobile/android/focus-android/app/src/test/java/org/mozilla/focus/utils/SupportUtilsTest.kt
+++ b/mobile/android/focus-android/app/src/test/java/org/mozilla/focus/utils/SupportUtilsTest.kt
@@ -4,14 +4,8 @@
 
 package org.mozilla.focus.utils
 
-import android.content.Context
-import android.content.pm.PackageInfo
-import android.content.pm.PackageManager
 import org.junit.Assert.assertEquals
-import org.junit.Assert.assertThrows
 import org.junit.Test
-import org.mockito.Mockito.mock
-import org.mockito.Mockito.`when`
 import java.util.Locale
 
 class SupportUtilsTest {
@@ -67,47 +61,4 @@ class SupportUtilsTest {
             SupportUtils.manifestoURL,
         )
     }
-
-    @Test
-    fun `appVersionName returns proper value`() {
-        val context: Context = mock()
-        val packageManager: PackageManager = mock()
-        val packageInfo = PackageInfo().apply { versionName = "1.0.0" }
-
-        `when`(context.packageManager).thenReturn(packageManager)
-        `when`(context.packageName).thenReturn("org.mozilla.focus")
-        `when`(packageManager.getPackageInfo("org.mozilla.focus", 0)).thenReturn(packageInfo)
-
-        val version = SupportUtils.getAppVersion(context)
-        assertEquals("1.0.0", version)
-    }
-
-    @Test
-    fun `appVersionName returns empty string when versionName is null`() {
-        val context: Context = mock()
-        val packageManager: PackageManager = mock()
-        val packageInfo = PackageInfo().apply { versionName = null }
-
-        `when`(context.packageManager).thenReturn(packageManager)
-        `when`(context.packageName).thenReturn("org.mozilla.focus")
-        `when`(packageManager.getPackageInfo("org.mozilla.focus", 0)).thenReturn(packageInfo)
-
-        val version = SupportUtils.getAppVersion(context)
-        assertEquals("", version)
-    }
-
-    @Test
-    fun `appVersionName throws IllegalStateException when package not found`() {
-        val context: Context = mock()
-        val packageManager: PackageManager = mock()
-
-        `when`(context.packageManager).thenReturn(packageManager)
-        `when`(context.packageName).thenReturn("org.mozilla.focus")
-        `when`(packageManager.getPackageInfo("org.mozilla.focus", 0))
-            .thenThrow(PackageManager.NameNotFoundException::class.java)
-
-        assertThrows(IllegalStateException::class.java) {
-            SupportUtils.getAppVersion(context)
-        }
-    }
 }
diff --git a/mobile/android/geckoview/src/main/java/org/mozilla/geckoview/doc-files/CHANGELOG.md b/mobile/android/geckoview/src/main/java/org/mozilla/geckoview/doc-files/CHANGELOG.md
index 70c094be663e..2fdb65595c8c 100644
--- a/mobile/android/geckoview/src/main/java/org/mozilla/geckoview/doc-files/CHANGELOG.md
+++ b/mobile/android/geckoview/src/main/java/org/mozilla/geckoview/doc-files/CHANGELOG.md
@@ -16,7 +16,6 @@ exclude: true
 ## v131
 - Added [`GeckoDisplay.windowInsetsChanged`][131.1].
 - Added [`GeckoView.addWindowInsetsListener`][131.2] and [`GeckoView.removeWindowInsetsListener`][131.3] to allow listening WindowInsets changes of Activity's root window with multiple listeners.
-- ⚠️Increased `compileSdkVersion` to 35 (Android 15)
 
 [131.1]: {{javadoc_uri}}/GeckoDisplay.html#windowInsetsChanged
 [131.2]: {{javadoc_uri}}/GeckoView.html#addWindowInsetsListener
diff --git a/python/mozboot/mozboot/android-packages.txt b/python/mozboot/mozboot/android-packages.txt
index eedd018ab306..a547d5dc2e75 100644
--- a/python/mozboot/mozboot/android-packages.txt
+++ b/python/mozboot/mozboot/android-packages.txt
@@ -1,4 +1,4 @@
 emulator
 platform-tools
-build-tools;35.0.0
-platforms;android-35
+build-tools;34.0.0
+platforms;android-34
diff --git a/testing/web-platform/tests/tools/wpt/android.py b/testing/web-platform/tests/tools/wpt/android.py
index e1eef88b6096..1e2d30fb389a 100644
--- a/testing/web-platform/tests/tools/wpt/android.py
+++ b/testing/web-platform/tests/tools/wpt/android.py
@@ -288,8 +288,8 @@ def install(logger, dest=None, reinstall=False, prompt=True):
 
         if new_install:
             packages = ["platform-tools",
-                        "build-tools;35.0.0",
-                        "platforms;android-35",
+                        "build-tools;34.0.0",
+                        "platforms;android-34",
                         "emulator"]
 
             install_android_packages(logger, paths, packages, prompt=prompt)