Don't go too aggressive disabling services and the Play Store, not all Apps and system components are updated via Samsung's Galaxy App Store. The Galaxy App Store also contains a number of unmaintained copies of popular apps which were never officially released on there by developers but submitted by end users who are fairly clueless or conversely are doing it on purpose with malware loaded in. While Samsung devices come preloaded with McAfee scanning capability it is about as much use as a chocolate fireguard.
Hmmmmm I seriously don't know either why it occurs and to end it all my s21 regular died on me the phone never turned back on kept dpkkg reboot mode so my network provider gave me S21 plus instead. I'm glad as it's bigger batter only 200mah less than S21Ultra but still good as.