Mines too. My m21 is having lots of issues regarding performance and battery. My m21 doesn't charge via fast charging now after the ONE UI 4.1 update ( I did try changing the socket/ cleaning the type C port / Using Another genuine Samsung fast charg...

I too am experiencing the same issue with my M21. The smoothness has been decreased alot after updating my phone to the android 12 (One UI 4.1) . Most of the time the device lags very much. Moreover the RAM management has become an unpleasant thing ...