iPhone restarts if SIM card inserted

Hey,

Sometime ago my iPhone restarted by itself and I thought it was some kind of overheating precaucion because I left it outside in the sun for a while.

However, it keeps restarting whenever I open any app now that has passed like a month since that time.

I recently discovered that it only restarts if I have my SIM card in it.

It starts, I unlock my SIM card and then when i open any app it just shuts down and restarts.

I appreciate if anyone could help me or advise me on how to fix it

Thank you