What does "enable full trust for root certificates" and why is it set to ON

Hello, no it's a personal phone I just got at the beginning of the year.

It has been giving me nothing but problems since I got it, especially after a nurse took it from me while I was in a procedure at the hospital and it was unlocked. She said she would turn it off but I got it back with a dead battery. I've had my eSIM deleted multiple times and both eSIM slots get taken up by business or travel lines and then deleted and my carrier claims it's just bugs or glitches but they've also asked me for my EID/SEID and both IMEI and even ICCID and hung up on me in the middle of calls. I apparently have voicemail according to notifications but my voicemail tab says nothing is there.

I've reformatted 7 times now and it keeps happening.

My settings say to trust all certificates and that it is managed and I've looked at my older iPhones and neither of them have this setting on them

???