Please make sure all your apps have been updated via the Playstore.
Remove any sd card just incase it's that which is causing issues.
If a phone is not behaving then things I suggest is …
1, First please put the phone in Safe Mode which disables your downloaded app's but let's your stock app's keep working. If the issues stop then this highlights a downloaded app as the possible issue. Come out of Safe Mode and start deleting your most recent downloaded app's one at a time until it stops.
2, Turn the phone Off and then from a set series of button presses go into the phone's system files and clear the system cache files. No information is lost this way.
3, Back up and factory reset after backing up and removing any relevant sd card.
A Samsung Experience Store or Samsung Service Centre can take a look.
I wish you all the best with this.
Current Phone ~
Samsung Note 20 Ultra 5G SM-N9860_256Gb SnapDragon 865+
Samsung One Ui 3.1/ Android 11.