Answer:
"iPhone restart loops can be caused by issues with your iPhone's connection to your wireless carrier. Your SIM card connects your iPhone to your wireless carrier, so removing it is best way to troubleshoot issues where your iPhone keeps restarting. Don't worry: Nothing can go wrong when you remove your SIM card."
Explanation:
copied and pasted from :
https://www.payetteforward.com/why-does-my-iphone-keep-restarting-heres-the-fix/#:~:text=iPhone%20restart%20loops%20can%20be,you%20remove%20your%20SIM%20card.
