diff --git a/gfx/layers/apz/util/APZEventState.cpp b/gfx/layers/apz/util/APZEventState.cpp
index 9c170b35b717..a3f3ae4b27a1 100644
--- a/gfx/layers/apz/util/APZEventState.cpp
+++ b/gfx/layers/apz/util/APZEventState.cpp
@@ -497,7 +497,6 @@ void APZEventState::ProcessAPZStateChange(ViewID aViewId,
           nsLayoutUtils::FindScrollContainerFrameFor(aViewId);
       if (sf) {
         sf->SetTransformingByAPZ(true);
-        sf->ScrollbarActivityStarted();
       }
 
       nsIContent* content = nsLayoutUtils::FindContentFor(aViewId);
@@ -514,7 +513,6 @@ void APZEventState::ProcessAPZStateChange(ViewID aViewId,
           nsLayoutUtils::FindScrollContainerFrameFor(aViewId);
       if (sf) {
         sf->SetTransformingByAPZ(false);
-        sf->ScrollbarActivityStopped();
       }
 
       nsIContent* content = nsLayoutUtils::FindContentFor(aViewId);
diff --git a/layout/generic/ScrollContainerFrame.cpp b/layout/generic/ScrollContainerFrame.cpp
index a3f21ab67064..6199dcee9094 100644
--- a/layout/generic/ScrollContainerFrame.cpp
+++ b/layout/generic/ScrollContainerFrame.cpp
@@ -2296,12 +2296,18 @@ void ScrollContainerFrame::AsyncScrollCallback(ScrollContainerFrame* aInstance,
 }
 
 void ScrollContainerFrame::SetTransformingByAPZ(bool aTransforming) {
-  if (mTransformingByAPZ && !aTransforming) {
-    PostScrollEndEvent();
+  if (mTransformingByAPZ == aTransforming) {
+    return;
   }
   mTransformingByAPZ = aTransforming;
-  if (!mozilla::css::TextOverflow::HasClippedTextOverflow(this) ||
-      mozilla::css::TextOverflow::HasBlockEllipsis(mScrolledFrame)) {
+  if (aTransforming) {
+    ScrollbarActivityStarted();
+  } else {
+    ScrollbarActivityStopped();
+    PostScrollEndEvent();
+  }
+  if (!css::TextOverflow::HasClippedTextOverflow(this) ||
+      css::TextOverflow::HasBlockEllipsis(mScrolledFrame)) {
     // If the block has some overflow marker stuff we should kick off a paint
     // because we have special behaviour for it when APZ scrolling is active.
     SchedulePaint();
diff --git a/layout/generic/ScrollbarActivity.cpp b/layout/generic/ScrollbarActivity.cpp
index abebd90ea782..fda540d3bbd6 100644
--- a/layout/generic/ScrollbarActivity.cpp
+++ b/layout/generic/ScrollbarActivity.cpp
@@ -96,6 +96,8 @@ ScrollbarActivity::HandleEvent(dom::Event* aEvent) {
   nsAutoString type;
   aEvent->GetType(type);
 
+  auto* targetContent =
+      nsIContent::FromEventTargetOrNull(aEvent->GetOriginalTarget());
   if (type.EqualsLiteral("mousemove")) {
     // Mouse motions anywhere in the scrollable frame should keep the
     // scrollbars visible, but we have to be careful as content descendants of
@@ -105,8 +107,6 @@ ScrollbarActivity::HandleEvent(dom::Event* aEvent) {
     nsIFrame* scrollFrame = do_QueryFrame(mScrollableFrame);
     MOZ_ASSERT(scrollFrame);
     ScrollContainerFrame* scrollContainerFrame = do_QueryFrame(scrollFrame);
-    nsCOMPtr<nsIContent> targetContent =
-        do_QueryInterface(aEvent->GetOriginalTarget());
     nsIFrame* targetFrame =
         targetContent ? targetContent->GetPrimaryFrame() : nullptr;
     if ((scrollContainerFrame &&
@@ -120,9 +120,6 @@ ScrollbarActivity::HandleEvent(dom::Event* aEvent) {
     return NS_OK;
   }
 
-  nsCOMPtr<nsIContent> targetContent =
-      do_QueryInterface(aEvent->GetOriginalTarget());
-
   HandleEventForScrollbar(type, targetContent, GetHorizontalScrollbar(),
                           &mHScrollbarHovered);
   HandleEventForScrollbar(type, targetContent, GetVerticalScrollbar(),