In Tahoe, they broke that for 3rd party menu bar icons (and some Apple ones) See video: https://shot.3e.org/ss-20250918_074040.mp4

This worked fine until Tahoe.

It gets stranger, though - this is only broken if the menu bar is light-colored. That means it's broken if Reduce Transparency is turned on - OR if it's off, but you're using a very light (white or light gray) colored desktop background.

This isn't just the canary in a coal mine. The miners are dead. The mine has collapsed.