Same with me ...my phone was just of warranty they pushed and software update and now phone is frequently restarting .. I suspect this is strategy for earning royalty via support centre's..
This is same problem across many devices in Samsung..if it is under warranty.. please visit Samsung care .. I think will either fix software issue if not they can replace hardware
This is across many models of samsung .. I have m31 ...totally unstable after update due to continuous restart/crash problem..visited samsung centre .. nothing is working out