See https://github.com/Dart-Code/Dart-Code/issues/1173#issuecomment-582459854 and https://www.reddit.com/r/FlutterDev/comments/ez5yog/ive_been_having_trouble_with_vscode_recently_can/. This was made the default in the last release, but it's re-introduced https://github.com/Dart-Code/Dart-Code/issues/1173.