With that out of the way, this commonly-used part of Android has been around for years and remained mostly the same. In Android 12, it gets a slight design tweak that puts it a little higher up on the screen, at least on Pixels, and a tweaked font, too. More noticeably, the message now matches your system theme, meaning Android toast messages now support a dark theme. It’s a minor tweak, of course, but it’s one that really helps with overall consistency.
Notably, though, it only applies if the app generating the toast message supports dark theme.