iPhone 12 Turning On and Off Randomly Every Few Minutes or Hours

My iPhone 12 has been turning on and off randomly despite being fully charged for about 1 week now. The frequency of restarts has increased since updating my software. The phone is still under warranty, but if I can fix this phone, rather than get another under warranty, I would prefer that.

It turns off randomly on all different apps from google or apple maps, netflix or other streaming, safari, even during texting and when not in use at all. The phone has not been dropped in water (although apparently now that wouldn't be a problem), nor has any physical damage whatsoever.

As I live hours away from my family and recently had car problems, making my transportation to clinic and school dependent on my neighbor or classmates, having a functioning phone is pretty vital.

How can I troubleshoot this problem rather quickly? Did anyone found any solutions? I am desperate!