Same issue. Phone randomly restarts. Happens -it seems- only when not on WiFi.
Started after update to A13 / adding extra SIM. Not sure which one caused the issue.
I’ll try switching of 5G now and setting the 2nd SIM to 2G only to see if it helps.
Turning the 2nd SIM off seems to help until now.
Do simcards age?
MyFp4 worked fine since I bought it, spring 2022. So about 1 1/2 year.
Today it rebooted 7 times in the last half hour.
Don’t like that.
In a train, having 4g or 5g connections, never had this problem before.
Notice the op date… it was the release of android 12 when it started happening. It didn’t do it on 11…
And It hasn’t crashed since I and others switched 5g off… So it can’t be a hardware issue… like others have said to you…