There is a setting called Auto Restart in Device Care, which may be restarting your phone. If you don't want it to restart on its own (though it helps sometimes to fix problems), go to Settings > Device Care > Auto optimisation > Auto restart. You will find two options - Restart when needed and Restart on schedule. If you don't want it to restart on its own in either way, turn both the toggles off. If the issue persists, check the settings again.
If it still restarts on its own, raise an error report through the Members app by going to Members app > Help > Quick Help > Send feedback > Pencil button on bottom-right corner > Error report > Lock-up/restarting. There, write all the required information and if you're ok with it, send some device logs. Click Send. Then wait for a response.
If you want a quicker response, click Text chat under the same Quick Help section in Help tab. It will open Samsung Support's WhatsApp chat and text the number.
Kindly reset factory data with backup then try to it's again also turn off Auto restart in device care too. If not resolves issue then go to service center for check and resolves this issue. If you like please accept as a solution it's help to others users also, click on 3dots in my reply section and click on accept solution. Thanks.
