Good afternoon. I switched to the Samsung S21 Plus back in March '21. About 4 months into having it I dealt with what I've read to be 'the black screen of death'. I had a new phone replacement sent to me a couple days later under warranty. A few days into having my second S21 Plus it's now restarting on its own and has done it 5 times today. Tried the soft reset and going in and out of airplane mode briefly when I notice it freezing up. That's what Tech Support advised me to do as far as troubleshooting. I'm starting to wonder if I want this phone now tbh. My S10e gave me no issues for years. Anyone else deal with ongoing issues with this phone model?
I appreciate your continued the phone has been dented somewhat.
Please try Safe Mode.
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. https://www.samsung.com/uk/support/mobile-devices/how-to-start-my-galaxy-device-in-safe-mode/
Current Phone > Samsung Z Fold³ 5G.