Fixes #49480

src/vs/editor/browser/controller/textAreaState.ts

@@ -121,7 +121,7 @@ export class TextAreaState {
 			// See https://github.com/Microsoft/vscode/issues/42251
 			// where typing always happens at offset 0 in the textarea
 			// when using a custom title area in OSX and moving the window
-			if (strings.endsWith(currentValue, previousValue)) {
+			if (!strings.startsWith(currentValue, previousValue) && strings.endsWith(currentValue, previousValue)) {
 				// Looks like something was typed at offset 0
 				// ==> pretend we placed the cursor at offset 0 to begin with...
 				previousSelectionStart = 0;

src/vs/editor/test/browser/controller/textAreaState.test.ts

@@ -518,6 +518,20 @@ suite('TextAreaState', () => {
 		);
 	});
 
+	test('issue #49480: Double curly braces inserted', () => {
+		// Characters get doubled
+		testDeduceInput(
+			new TextAreaState(
+				'aa',
+				2, 2,
+				null, null
+			),
+			'aaa',
+			3, 3, true, true,
+			'a', 0
+		);
+	});
+
 	suite('PagedScreenReaderStrategy', () => {
 
 		function testPagedScreenReaderStrategy(lines: string[], selection: Selection, expected: TextAreaState): void {