please factory reset once then check....it's happening for software glitch..... I think basically you simply update software via mobile data or wifi which is not proper way to install software especially in samsung devices... samsung provides non A/B partition type ota software so anything mysterious can happened with device if someone simply update software..... it's process to install software via smart switch or from odin or through authorised samsung service center as they use odin only for their official purpose..
go to safemode and observe is there same issue in safemode too if not then problem may due to other downloaded apps and if same issue in safemode then try to visit service centre and get reinstall your software update
steps to turn safemode; long press on power button> long press on power off option>click on safemode >your mobile will restart and turn into safemode.
Keep in mind that in this mode only inbuilt system app will work
To resolve auto restart issue please follow below given steps: Go to Settings > General management > Reset > Turn off auto start.
For further assistance, register your concern in Samsung Members Application (Open Samsung Members Application > Get help > Send Feedback > Error report/Ask questions).
