It's been a couple of weeks since I installed oneui 4.0 android 12....
and the following have occurred
*poor battery life compared to oneui 3.1 android 11
*whatsapp unable to send videos compared to oneui 3.1 android 11
*general performance poor compared to oneui 3.1 android 11
*gallery app buggy compared to oneui 3.1 android 11
*overall system buggy compared to oneui 3.1 android 11
Samsung need to release a fix for the UK Samsung s21 5g ect
poor update and poor overall quality control management