I just installed the "fix patch" for TMobile galaxy S21 ultra, so far, the lag and refresh rate issue has been fixed for most apps, especially on Facebook.. the problems that remain:
Facebook, IG: i can't open external links from apps
Pandora: app won't open
Merrill Lynch: app won't open
I still can't play 2 sound apps at the same time unless i do it though the alternate sound assistant app.
Some apps are still crashing but I'm also getting more updates for many apps as time keeps passing by, maybe the 3rd party app developers are still updating their apps to Android 12.
So far this is what I'm still dealing with even after the first fix patch from TMobile