Specific JS construct breaks syntax highlighting

Does this issue occur when all extensions are disabled?: Yes

• VS Code Version: 1.81.0 / 6445d93c81ebe42c4cbd7a60712e0b17d9463e97
• OS Version: Windows_NT x64 10.0.19045

Snippet:

function one() {
	return (
		{
			toString: () => {
				return "Something";
			}
		}
	);
}

function two() {
	return "??";
}

Screenshot:

Steps to Reproduce:

1. Paste the following into a fresh file with JavaScript set as a language
2. Observe keyword highlighting not working correctly for any functions following function one

This specific nesting (a lambda function with a block inside a property of an object inside parenthesis in a return statement) triggers the effect.

Reproduce the issue in a fresh JavaScript file using the provided snippet and confirm that highlighting after function one is incorrect. Then inspect the TypeScript-TmLanguage grammar files for handling of nested object properties, arrow functions, and return statements; done means later functions receive correct keyword highlighting.