Thanks 

Thanks 

This issue isnt related to samsung its the an app issue lots of glitching , freezin and closing app

Or you could try to update your software thats if s21 ultra is eligible to update to ui 6

Most time the green screen is an issue coming from faulty hardware, hope your screen wasnt just replaced and as for adaptive smoothness you can check if screen is using 120 hz after activating developer options by opening settings, open about phone t...