Modern UI designers seem to struggle with one simple idea: constrained space along an axis.
On mobile, horizontal space is constrained, but vertical is plentiful. Don't place multiple text views next to each other when they contain a potentially long str... Just don...
On desktop, it's the reverse. Screens are wider than they are tall, and various system/browser panels already eat into the available height. So a fixed header on a desktop website is never, ever a good idea.
(besides, the Android 12 update itself is just plain superfluous — I'm staying on 11 for the time being, thank you very much Google, now go fuck yourself and especially your designers)