use one style for unexpected outcome, disable by default, #85376

src/vs/editor/common/config/editorOptions.ts

@@ -2395,7 +2395,7 @@ export interface ISuggestOptions {
 	 */
 	insertMode?: 'insert' | 'replace';
 	/**
-	 * Show a highlight when suggestion replaces or keep text after the cursor. Defaults to true.
+	 * Show a highlight when suggestion replaces or keep text after the cursor. Defaults to false.
 	 */
 	insertHighlight?: boolean;
 	/**
@@ -2531,7 +2531,7 @@ class EditorSuggest extends BaseEditorOption<EditorOption.suggest, InternalSugge
 	constructor() {
 		const defaults: InternalSuggestOptions = {
 			insertMode: 'insert',
-			insertHighlight: true,
+			insertHighlight: false,
 			filterGraceful: true,
 			snippetsPreventQuickSuggestions: true,
 			localityBonus: false,

src/vs/editor/contrib/suggest/media/suggest.css

@@ -280,10 +280,7 @@
 
 /* replace/insert decorations */
 
-.monaco-editor .suggest-insertMode-goes {
-	text-decoration-line: line-through;
-}
-
-.monaco-editor .suggest-insertMode-stays {
+.monaco-editor .suggest-insert-unexpected {
 	font-style: italic;
 }
+

src/vs/editor/contrib/suggest/suggestRangeHighlighter.ts

@@ -74,7 +74,7 @@ export class SuggestRangeHighlighter {
 				// wants inserts but got replace-mode -> highlight AFTER range
 				newDeco = [{
 					range: new Range(position.lineNumber, position.column, position.lineNumber, position.column + info.overwriteAfter),
-					options: { inlineClassName: 'suggest-insertMode-goes' }
+					options: { inlineClassName: 'suggest-insert-unexpected' }
 				}];
 
 			} else if (opts.insertMode === 'replace' && info.overwriteAfter === 0) {
@@ -83,7 +83,7 @@ export class SuggestRangeHighlighter {
 				if (wordInfo && wordInfo.endColumn > position.column) {
 					newDeco = [{
 						range: new Range(position.lineNumber, position.column, position.lineNumber, wordInfo.endColumn),
-						options: { inlineClassName: 'suggest-insertMode-stays' }
+						options: { inlineClassName: 'suggest-insert-unexpected' }
 					}];
 				}
 			}

src/vs/monaco.d.ts

@@ -3400,7 +3400,7 @@ declare namespace monaco.editor {
 		 */
 		insertMode?: 'insert' | 'replace';
 		/**
-		 * Show a highlight when suggestion replaces or keep text after the cursor. Defaults to true.
+		 * Show a highlight when suggestion replaces or keep text after the cursor. Defaults to false.
 		 */
 		insertHighlight?: boolean;
 		/**