diff --git a/editor/libeditor/HTMLEditSubActionHandler.cpp b/editor/libeditor/HTMLEditSubActionHandler.cpp
index 2cb79eed4b32..c537444a1a43 100644
--- a/editor/libeditor/HTMLEditSubActionHandler.cpp
+++ b/editor/libeditor/HTMLEditSubActionHandler.cpp
@@ -560,9 +560,9 @@ nsresult HTMLEditor::OnEndHandlingTopLevelEditSubActionInternal() {
         case EditSubAction::eInsertText:
         case EditSubAction::eInsertTextComingFromIME:
         case EditSubAction::eInsertLineBreak:
+        case EditSubAction::eInsertParagraphSeparator:
           return !StaticPrefs::
               editor_white_space_normalization_blink_compatible();
-        case EditSubAction::eInsertParagraphSeparator:
         case EditSubAction::ePasteHTMLContent:
         case EditSubAction::eInsertHTMLSource:
           return true;
@@ -2305,7 +2305,7 @@ HTMLEditor::InsertParagraphSeparatorAsSubAction(const Element& aEditingHost) {
 
 Result<CreateElementResult, nsresult> HTMLEditor::HandleInsertBRElement(
     const EditorDOMPoint& aPointToBreak, const Element& aEditingHost) {
-  MOZ_ASSERT(aPointToBreak.IsSet());
+  MOZ_ASSERT(aPointToBreak.IsInContentNode());
   MOZ_ASSERT(IsEditActionDataAvailable());
 
   const bool editingHostIsEmpty = HTMLEditUtils::IsEmptyNode(
@@ -2365,6 +2365,8 @@ Result<CreateElementResult, nsresult> HTMLEditor::HandleInsertBRElement(
     RefPtr<Element> linkNode =
         HTMLEditor::GetLinkElement(pointToBreak.GetContainer());
     if (linkNode) {
+      // FIXME: Normalize surrounding white-spaces before splitting the
+      // insertion point here.
       Result<SplitNodeResult, nsresult> splitLinkNodeResult =
           SplitNodeDeepWithTransaction(
               *linkNode, pointToBreak,
@@ -2716,6 +2718,26 @@ Result<CaretPoint, nsresult> HTMLEditor::HandleInsertParagraphInMailCiteElement(
       return Err(NS_ERROR_FAILURE);
     }
 
+    if (StaticPrefs::editor_white_space_normalization_blink_compatible()) {
+      Result<EditorDOMPoint, nsresult> pointToSplitOrError =
+          WhiteSpaceVisibilityKeeper::NormalizeWhiteSpacesToSplitAt(
+              *this, pointToSplit,
+              {WhiteSpaceVisibilityKeeper::NormalizeOption::
+                   StopIfPrecedingWhiteSpacesEndsWithNBP,
+               WhiteSpaceVisibilityKeeper::NormalizeOption::
+                   StopIfFollowingWhiteSpacesStartsWithNBSP});
+      if (MOZ_UNLIKELY(pointToSplitOrError.isErr())) {
+        NS_WARNING(
+            "WhiteSpaceVisibilityKeeper::NormalizeWhiteSpacesToSplitAt() "
+            "failed");
+        return pointToSplitOrError.propagateErr();
+      }
+      pointToSplit = pointToSplitOrError.unwrap();
+      if (NS_WARN_IF(!pointToSplit.IsInContentNode())) {
+        return Err(NS_ERROR_EDITOR_UNEXPECTED_DOM_TREE);
+      }
+    }
+
     Result<SplitNodeResult, nsresult> splitResult =
         SplitNodeDeepWithTransaction(aMailCiteElement, pointToSplit,
                                      SplitAtEdges::eDoNotCreateEmptyContainer);
@@ -9005,6 +9027,7 @@ Result<SplitNodeResult, nsresult> HTMLEditor::HandleInsertParagraphInParagraph(
       if (pointToInsertBR.IsInContentNode() &&
           HTMLEditUtils::CanNodeContain(
               *pointToInsertBR.ContainerAs<nsIContent>(), *nsGkAtoms::br)) {
+        AutoTrackDOMPoint trackPointToSplit(RangeUpdaterRef(), &pointToSplit);
         Result<CreateLineBreakResult, nsresult> insertBRElementResultOrError =
             InsertLineBreak(WithTransaction::Yes, LineBreakType::BRElement,
                             pointToInsertBR);
@@ -9020,6 +9043,10 @@ Result<SplitNodeResult, nsresult> HTMLEditor::HandleInsertParagraphInParagraph(
         // SplitParagraphWithTransaction.
         insertBRElementResult.IgnoreCaretPointSuggestion();
         brElement = &insertBRElementResult->BRElementRef();
+        trackPointToSplit.FlushAndStopTracking();
+        if (NS_WARN_IF(!pointToSplit.IsInContentNodeAndValidInComposedDoc())) {
+          return Err(NS_ERROR_EDITOR_UNEXPECTED_DOM_TREE);
+        }
       }
     }
   } else {
diff --git a/editor/libeditor/HTMLEditor.cpp b/editor/libeditor/HTMLEditor.cpp
index 4365cb885b96..7ae5c78ef675 100644
--- a/editor/libeditor/HTMLEditor.cpp
+++ b/editor/libeditor/HTMLEditor.cpp
@@ -4394,7 +4394,9 @@ Result<EditorDOMPoint, nsresult> HTMLEditor::PrepareToInsertLineBreak(
     }
     Result<EditorDOMPoint, nsresult> pointToInsertOrError =
         WhiteSpaceVisibilityKeeper::NormalizeWhiteSpacesToSplitAt(
-            *this, aPointToInsert);
+            *this, aPointToInsert,
+            {WhiteSpaceVisibilityKeeper::NormalizeOption::
+                 StopIfPrecedingWhiteSpacesEndsWithNBP});
     if (NS_WARN_IF(pointToInsertOrError.isErr())) {
       return pointToInsertOrError.propagateErr();
     }
@@ -4413,7 +4415,9 @@ Result<EditorDOMPoint, nsresult> HTMLEditor::PrepareToInsertLineBreak(
   Result<EditorDOMPoint, nsresult> pointToInsertOrError =
       StaticPrefs::editor_white_space_normalization_blink_compatible()
           ? WhiteSpaceVisibilityKeeper::NormalizeWhiteSpacesToSplitAt(
-                *this, aPointToInsert)
+                *this, aPointToInsert,
+                {WhiteSpaceVisibilityKeeper::NormalizeOption::
+                     StopIfPrecedingWhiteSpacesEndsWithNBP})
           : aPointToInsert;
   if (NS_WARN_IF(pointToInsertOrError.isErr())) {
     return pointToInsertOrError.propagateErr();
diff --git a/editor/libeditor/WhiteSpaceVisibilityKeeper.cpp b/editor/libeditor/WhiteSpaceVisibilityKeeper.cpp
index 050bfe14acf9..caa97cc8ba80 100644
--- a/editor/libeditor/WhiteSpaceVisibilityKeeper.cpp
+++ b/editor/libeditor/WhiteSpaceVisibilityKeeper.cpp
@@ -47,7 +47,7 @@ Result<EditorDOMPoint, nsresult>
 WhiteSpaceVisibilityKeeper::PrepareToSplitBlockElement(
     HTMLEditor& aHTMLEditor, const EditorDOMPoint& aPointToSplit,
     const Element& aSplittingBlockElement) {
-  if (NS_WARN_IF(!aPointToSplit.IsInContentNode()) ||
+  if (NS_WARN_IF(!aPointToSplit.IsInContentNodeAndValidInComposedDoc()) ||
       NS_WARN_IF(!HTMLEditUtils::IsSplittableNode(aSplittingBlockElement)) ||
       NS_WARN_IF(!EditorUtils::IsEditableContent(
           *aPointToSplit.ContainerAs<nsIContent>(), EditorType::HTML))) {
@@ -69,7 +69,8 @@ WhiteSpaceVisibilityKeeper::PrepareToSplitBlockElement(
     pointToSplit.Set(content);
   }
 
-  {
+  // TODO: Delete this block once we ship the new normalizer.
+  if (!StaticPrefs::editor_white_space_normalization_blink_compatible()) {
     AutoTrackDOMPoint tracker(aHTMLEditor.RangeUpdaterRef(), &pointToSplit);
 
     nsresult rv = WhiteSpaceVisibilityKeeper::
@@ -84,6 +85,21 @@ WhiteSpaceVisibilityKeeper::PrepareToSplitBlockElement(
           "MakeSureToKeepVisibleWhiteSpacesVisibleAfterSplit() failed");
       return Err(rv);
     }
+  } else {
+    // NOTE: Chrome does not normalize white-spaces at splitting `Text` when
+    // inserting a paragraph at least when the surrounding white-spaces being or
+    // end with an NBSP.
+    Result<EditorDOMPoint, nsresult> pointToSplitOrError =
+        WhiteSpaceVisibilityKeeper::NormalizeWhiteSpacesToSplitAt(
+            aHTMLEditor, pointToSplit,
+            {NormalizeOption::StopIfFollowingWhiteSpacesStartsWithNBSP,
+             NormalizeOption::StopIfPrecedingWhiteSpacesEndsWithNBP});
+    if (MOZ_UNLIKELY(pointToSplitOrError.isErr())) {
+      NS_WARNING(
+          "WhiteSpaceVisibilityKeeper::NormalizeWhiteSpacesToSplitAt() failed");
+      return pointToSplitOrError.propagateErr();
+    }
+    pointToSplit = pointToSplitOrError.unwrap();
   }
 
   if (NS_WARN_IF(!pointToSplit.IsInContentNode()) ||
@@ -821,7 +837,8 @@ Result<MoveNodeResult, nsresult> WhiteSpaceVisibilityKeeper::
 // static
 Result<EditorDOMPoint, nsresult>
 WhiteSpaceVisibilityKeeper::NormalizeWhiteSpacesToSplitTextNodeAt(
-    HTMLEditor& aHTMLEditor, const EditorDOMPointInText& aPointToSplit) {
+    HTMLEditor& aHTMLEditor, const EditorDOMPointInText& aPointToSplit,
+    NormalizeOptions aOptions) {
   MOZ_ASSERT(aPointToSplit.IsSetAndValid());
   MOZ_ASSERT(StaticPrefs::editor_white_space_normalization_blink_compatible());
 
@@ -855,13 +872,18 @@ WhiteSpaceVisibilityKeeper::NormalizeWhiteSpacesToSplitTextNodeAt(
 
   const HTMLEditor::ReplaceWhiteSpacesData replacePrecedingWhiteSpacesData =
       aPointToSplit.IsStartOfContainer() ||
-              // Chrome does not normalize the left `Text` at least when it ends
-              // with an NBSP.
-              aPointToSplit.IsPreviousCharNBSP()
+              (aOptions.contains(
+                   NormalizeOption::StopIfPrecedingWhiteSpacesEndsWithNBP) &&
+               aPointToSplit.IsPreviousCharNBSP())
           ? HTMLEditor::ReplaceWhiteSpacesData()
           : aHTMLEditor.GetPrecedingNormalizedStringToSplitAt(aPointToSplit);
   const HTMLEditor::ReplaceWhiteSpacesData replaceFollowingWhiteSpaceData =
-      aHTMLEditor.GetFollowingNormalizedStringToSplitAt(aPointToSplit);
+      aPointToSplit.IsEndOfContainer() ||
+              (aOptions.contains(
+                   NormalizeOption::StopIfFollowingWhiteSpacesStartsWithNBSP) &&
+               aPointToSplit.IsCharNBSP())
+          ? HTMLEditor::ReplaceWhiteSpacesData()
+          : aHTMLEditor.GetFollowingNormalizedStringToSplitAt(aPointToSplit);
   const HTMLEditor::ReplaceWhiteSpacesData replaceWhiteSpacesData =
       (replacePrecedingWhiteSpacesData + replaceFollowingWhiteSpaceData)
           .GetMinimizedData(*textNode);
@@ -904,7 +926,8 @@ WhiteSpaceVisibilityKeeper::NormalizeWhiteSpacesToSplitTextNodeAt(
 // static
 Result<EditorDOMPoint, nsresult>
 WhiteSpaceVisibilityKeeper::NormalizeWhiteSpacesToSplitAt(
-    HTMLEditor& aHTMLEditor, const EditorDOMPoint& aPointToSplit) {
+    HTMLEditor& aHTMLEditor, const EditorDOMPoint& aPointToSplit,
+    NormalizeOptions aOptions) {
   MOZ_ASSERT(aPointToSplit.IsSet());
   MOZ_ASSERT(StaticPrefs::editor_white_space_normalization_blink_compatible());
 
@@ -936,7 +959,7 @@ WhiteSpaceVisibilityKeeper::NormalizeWhiteSpacesToSplitAt(
   if (pointToSplit.IsInTextNode()) {
     Result<EditorDOMPoint, nsresult> pointToSplitOrError =
         WhiteSpaceVisibilityKeeper::NormalizeWhiteSpacesToSplitTextNodeAt(
-            aHTMLEditor, pointToSplit.AsInText());
+            aHTMLEditor, pointToSplit.AsInText(), aOptions);
     if (MOZ_UNLIKELY(pointToSplitOrError.isErr())) {
       NS_WARNING(
           "WhiteSpaceVisibilityKeeper::NormalizeWhiteSpacesToSplitTextNodeAt() "
@@ -981,11 +1004,9 @@ WhiteSpaceVisibilityKeeper::NormalizeWhiteSpacesToSplitAt(
             textNode->TextDataLength()) {
           break;
         }
-        // Chrome does not normalize preceding `Text` at least when it ends with
-        // an NBSP.
-        if (textNode->TextDataLength() &&
-            textNode->TextFragment().CharAt(textNode->TextLength() - 1u) ==
-                HTMLEditUtils::kNBSP) {
+        if (aOptions.contains(
+                NormalizeOption::StopIfPrecedingWhiteSpacesEndsWithNBP) &&
+            textNode->TextFragment().SafeLastChar() == HTMLEditUtils::kNBSP) {
           break;
         }
         precedingTextNodes.AppendElement(*textNode);
@@ -1021,6 +1042,11 @@ WhiteSpaceVisibilityKeeper::NormalizeWhiteSpacesToSplitAt(
             textNode->TextDataLength()) {
           break;
         }
+        if (aOptions.contains(
+                NormalizeOption::StopIfFollowingWhiteSpacesStartsWithNBSP) &&
+            textNode->TextFragment().SafeFirstChar() == HTMLEditUtils::kNBSP) {
+          break;
+        }
         followingTextNodes.AppendElement(*textNode);
         if (textNode->TextIsOnlyWhitespace() &&
             EditorUtils::IsWhiteSpacePreformatted(*textNode)) {
@@ -1045,7 +1071,7 @@ WhiteSpaceVisibilityKeeper::NormalizeWhiteSpacesToSplitAt(
   for (const auto& textNode : precedingTextNodes) {
     Result<EditorDOMPoint, nsresult> normalizeWhiteSpacesResultOrError =
         WhiteSpaceVisibilityKeeper::NormalizeWhiteSpacesToSplitTextNodeAt(
-            aHTMLEditor, EditorDOMPointInText::AtEndOf(textNode));
+            aHTMLEditor, EditorDOMPointInText::AtEndOf(textNode), aOptions);
     if (MOZ_UNLIKELY(normalizeWhiteSpacesResultOrError.isErr())) {
       NS_WARNING(
           "WhiteSpaceVisibilityKeeper::NormalizeWhiteSpacesToSplitTextNodeAt() "
@@ -1062,7 +1088,7 @@ WhiteSpaceVisibilityKeeper::NormalizeWhiteSpacesToSplitAt(
   for (const auto& textNode : followingTextNodes) {
     Result<EditorDOMPoint, nsresult> normalizeWhiteSpacesResultOrError =
         WhiteSpaceVisibilityKeeper::NormalizeWhiteSpacesToSplitTextNodeAt(
-            aHTMLEditor, EditorDOMPointInText(textNode, 0u));
+            aHTMLEditor, EditorDOMPointInText(textNode, 0u), aOptions);
     if (MOZ_UNLIKELY(normalizeWhiteSpacesResultOrError.isErr())) {
       NS_WARNING(
           "WhiteSpaceVisibilityKeeper::NormalizeWhiteSpacesToSplitTextNodeAt() "
@@ -1295,10 +1321,13 @@ WhiteSpaceVisibilityKeeper::InsertLineBreak(
       }
     }
   } else {
+    // Chrome does not normalize preceding white-spaces at least when it ends
+    // with an NBSP.
     Result<EditorDOMPoint, nsresult>
         normalizeSurroundingWhiteSpacesResultOrError =
             WhiteSpaceVisibilityKeeper::NormalizeWhiteSpacesToSplitAt(
-                aHTMLEditor, aPointToInsert);
+                aHTMLEditor, aPointToInsert,
+                {NormalizeOption::StopIfPrecedingWhiteSpacesEndsWithNBP});
     if (MOZ_UNLIKELY(normalizeSurroundingWhiteSpacesResultOrError.isErr())) {
       NS_WARNING(
           "WhiteSpaceVisibilityKeeper::NormalizeWhiteSpacesToSplitAt() failed");
diff --git a/editor/libeditor/WhiteSpaceVisibilityKeeper.h b/editor/libeditor/WhiteSpaceVisibilityKeeper.h
index ebb3035e8c2f..76b2f66ab435 100644
--- a/editor/libeditor/WhiteSpaceVisibilityKeeper.h
+++ b/editor/libeditor/WhiteSpaceVisibilityKeeper.h
@@ -130,6 +130,14 @@ class WhiteSpaceVisibilityKeeper final {
                              const EditorDOMPoint& aPointToSplit,
                              const Element& aSplittingBlockElement);
 
+  enum class NormalizeOption {
+    // If set, don't normalize following white-spaces if starts with an NBSP.
+    StopIfFollowingWhiteSpacesStartsWithNBSP,
+    // If set, don't normalize preceding white-spaces if ends with an NBSP.
+    StopIfPrecedingWhiteSpacesEndsWithNBP,
+  };
+  using NormalizeOptions = EnumSet<NormalizeOption>;
+
   /**
    * Normalize surrounding white-spaces of aPointToSplit.  This may normalize
    * 2 `Text` nodes if the point is surrounded by them.
@@ -137,7 +145,8 @@ class WhiteSpaceVisibilityKeeper final {
    */
   [[nodiscard]] MOZ_CAN_RUN_SCRIPT static Result<EditorDOMPoint, nsresult>
   NormalizeWhiteSpacesToSplitAt(HTMLEditor& aHTMLEditor,
-                                const EditorDOMPoint& aPointToSplit);
+                                const EditorDOMPoint& aPointToSplit,
+                                NormalizeOptions aOptions);
 
   /**
    * MergeFirstLineOfRightBlockElementIntoDescendantLeftBlockElement() merges
@@ -365,7 +374,8 @@ class WhiteSpaceVisibilityKeeper final {
    */
   [[nodiscard]] MOZ_CAN_RUN_SCRIPT static Result<EditorDOMPoint, nsresult>
   NormalizeWhiteSpacesToSplitTextNodeAt(
-      HTMLEditor& aHTMLEditor, const EditorDOMPointInText& aPointToSplit);
+      HTMLEditor& aHTMLEditor, const EditorDOMPointInText& aPointToSplit,
+      NormalizeOptions aOptions);
 
   /**
    * Delete leading or trailing invisible white-spaces around block boundaries