Windows 11 beta builds have a bug that swaps the startup sound with Vista's. Brandon LeBlanc confirmed the bug and clarified it wasn't intentional.

The .WAV file for the bootup sound, which is stored inside imageres.dll, had been randomly replaced with the Windows Vista startup sound in preview build 26200.5651.

If you use one of the recent Windows 11 preview builds, you might have noticed a different startup sound. As it turned out, Microsoft accidentally replaced it with the old-school Windows Vista jingle.