diff --git a/src/vs/workbench/api/browser/mainThreadNotebook.ts b/src/vs/workbench/api/browser/mainThreadNotebook.ts
index fcde89ecbb4..1a2b21cf966 100644
--- a/src/vs/workbench/api/browser/mainThreadNotebook.ts
+++ b/src/vs/workbench/api/browser/mainThreadNotebook.ts
@@ -602,18 +602,6 @@ export class MainThreadNotebooks extends Disposable implements MainThreadNoteboo
 		return false;
 	}
 
-	$onContentChange(resource: UriComponents, viewType: string): void {
-		const textModel = this._notebookService.getNotebookTextModel(URI.from(resource));
-
-		if (textModel) {
-			textModel.applyEdits(textModel.versionId, [
-				{
-					editType: CellEditType.Unknown
-				}
-			], true, undefined, () => undefined, undefined);
-		}
-	}
-
 	async $tryRevealRange(id: string, range: ICellRange, revealType: NotebookEditorRevealType) {
 		const editor = this._notebookService.listNotebookEditors().find(editor => editor.getId() === id);
 		if (editor && editor.isNotebookEditor) {
diff --git a/src/vs/workbench/api/common/extHost.protocol.ts b/src/vs/workbench/api/common/extHost.protocol.ts
index ebda6d1a322..aa338df4341 100644
--- a/src/vs/workbench/api/common/extHost.protocol.ts
+++ b/src/vs/workbench/api/common/extHost.protocol.ts
@@ -809,7 +809,6 @@ export interface MainThreadNotebookShape extends IDisposable {
 	$registerNotebookEditorDecorationType(key: string, options: INotebookDecorationRenderOptions): void;
 	$removeNotebookEditorDecorationType(key: string): void;
 	$trySetDecorations(id: string, range: ICellRange, decorationKey: string): void;
-	$onContentChange(resource: UriComponents, viewType: string): void;
 }
 
 export interface MainThreadUrlsShape extends IDisposable {
diff --git a/src/vs/workbench/api/common/extHostNotebookEditor.ts b/src/vs/workbench/api/common/extHostNotebookEditor.ts
index 60e3af8a293..b7cfa39c6c0 100644
--- a/src/vs/workbench/api/common/extHostNotebookEditor.ts
+++ b/src/vs/workbench/api/common/extHostNotebookEditor.ts
@@ -208,7 +208,7 @@ export class ExtHostNotebookEditor extends Disposable implements vscode.Notebook
 
 			if (prev.editType === CellEditType.Replace && editData.cellEdits[i].editType === CellEditType.Replace) {
 				const edit = editData.cellEdits[i];
-				if ((edit.editType !== CellEditType.DocumentMetadata && edit.editType !== CellEditType.Unknown) && prev.index === edit.index) {
+				if ((edit.editType !== CellEditType.DocumentMetadata) && prev.index === edit.index) {
 					prev.cells.push(...(editData.cellEdits[i] as ICellReplaceEdit).cells);
 					prev.count += (editData.cellEdits[i] as ICellReplaceEdit).count;
 					continue;
diff --git a/src/vs/workbench/contrib/notebook/common/model/notebookTextModel.ts b/src/vs/workbench/contrib/notebook/common/model/notebookTextModel.ts
index ff19d9eb4f3..7ad9daf8e00 100644
--- a/src/vs/workbench/contrib/notebook/common/model/notebookTextModel.ts
+++ b/src/vs/workbench/contrib/notebook/common/model/notebookTextModel.ts
@@ -3,7 +3,6 @@
  *  Licensed under the MIT License. See License.txt in the project root for license information.
  *--------------------------------------------------------------------------------------------*/
 
-import * as nls from 'vs/nls';
 import { Emitter, Event } from 'vs/base/common/event';
 import { Disposable, dispose, IDisposable } from 'vs/base/common/lifecycle';
 import { URI } from 'vs/base/common/uri';
@@ -314,7 +313,7 @@ export class NotebookTextModel extends Disposable implements INotebookTextModel
 			return {
 				edit,
 				end:
-					(edit.editType === CellEditType.DocumentMetadata || edit.editType === CellEditType.Unknown)
+					(edit.editType === CellEditType.DocumentMetadata)
 						? undefined
 						: (edit.editType === CellEditType.Replace ? edit.index + edit.count : edit.index),
 				originalIndex: index,
@@ -364,9 +363,6 @@ export class NotebookTextModel extends Disposable implements INotebookTextModel
 				case CellEditType.Move:
 					this._moveCellToIdx(edit.index, edit.length, edit.newIdx, synchronous, computeUndoRedo, undefined, undefined);
 					break;
-				case CellEditType.Unknown:
-					this._handleUnknownChange();
-					break;
 			}
 		}
 
@@ -380,32 +376,6 @@ export class NotebookTextModel extends Disposable implements INotebookTextModel
 		return new NotebookTextModelSnapshot(this);
 	}
 
-	handleUnknownUndoableEdit(label: string | undefined, undo: () => void, redo: () => void): void {
-		this._operationManager.pushEditOperation({
-			type: UndoRedoElementType.Resource,
-			resource: this.uri,
-			label: label ?? nls.localize('defaultEditLabel', "Edit"),
-			undo: async () => {
-				undo();
-			},
-			redo: async () => {
-				redo();
-			},
-		}, undefined, undefined);
-
-		this._eventEmitter.emit({
-			kind: NotebookCellsChangeType.Unknown,
-			transient: false
-		}, true);
-	}
-
-	private _handleUnknownChange() {
-		this._eventEmitter.emit({
-			kind: NotebookCellsChangeType.Unknown,
-			transient: false
-		}, true);
-	}
-
 	private _replaceCells(index: number, count: number, cellDtos: ICellDto2[], synchronous: boolean, computeUndoRedo: boolean): void {
 
 		if (count === 0 && cellDtos.length === 0) {
diff --git a/src/vs/workbench/contrib/notebook/common/notebookCommon.ts b/src/vs/workbench/contrib/notebook/common/notebookCommon.ts
index c9d8c53abf0..cf462b90514 100644
--- a/src/vs/workbench/contrib/notebook/common/notebookCommon.ts
+++ b/src/vs/workbench/contrib/notebook/common/notebookCommon.ts
@@ -444,11 +444,7 @@ export interface ICellMoveEdit {
 	newIdx: number;
 }
 
-export interface IDocumentUnknownEdit {
-	editType: CellEditType.Unknown;
-}
-
-export type ICellEditOperation = ICellReplaceEdit | ICellOutputEdit | ICellMetadataEdit | ICellLanguageEdit | IDocumentMetadataEdit | ICellOutputsSpliceEdit | ICellMoveEdit | IDocumentUnknownEdit;
+export type ICellEditOperation = ICellReplaceEdit | ICellOutputEdit | ICellMetadataEdit | ICellLanguageEdit | IDocumentMetadataEdit | ICellOutputsSpliceEdit | ICellMoveEdit;
 
 export interface INotebookEditData {
 	documentVersionId: number;