iphone battery issues

a couple days ago i was using my iphone 13 mini while charging it(battery percentage was less than 15 percent) and it suddenly went off and restarted almost immediately. when it came back on, iphone wouldn't charge and i got a warning showing "unknown battery part". battery percentage was now at 0% and the iphone went off couple seconds after. All these happened while my iphone was still plugged in. Battery health wasn't available thereafter but as of that the day before it was still at 91%. My iphone is just 13months old.

my question is could it be that my battery has gone bad at 91% health or it's a charging issue??(i doubt this though coz it kept coming on everytime i plugged it in but would go off few seconds after it had fully booted)