I did the same on Tahoe and now the formerly glass buttons are grey with a weird blue shadow in the upper left. One example: the sound slider on the menu bar. With all the GFX turned on, it is a transparent blob, with the reduced settings, it's just a weird gray with a nonsensical shadow.

I'd really, really love to read internal presentations leading up to this downgrade of a once proud UI (let's hear it for System 7) to what is now effectively a collection childish digital baubles.