black loading screen with lock screen flashing?

has anyone else had the problem with when you exit out of an app (like completely close out/quit the app) and your phone goes black for a second (literally a second) and then flashes your lock screen the goes back to the black screen with the loading sign (🔅 like this?) and constantly flashes between black screen and lock screen? it lasts anywhere from 1-20 minutes and happens multiple (6 separate occurrences so far today) times a day. i have an iphone 12. it’s updated and i have tried fixing it by completely resetting the entire phone and making sure my storage isn’t full. nothing fixes it. i’ve only had this phone since october and it’s never had any cracks, water damage, drops etc. it’s always in a protective case. do i need to get the phone replaced? what do i need to do?

HELP!!!!

😩