Samsung Galaxy F23 Back Panel Bulging Issue

I am using a Samsung Galaxy F23 and I have recently noticed that the back panel of the phone is becoming slightly flexible and has developed a small bump in the middle. The phone is still working normally, but the back does not feel as firm as it used to.

Has anyone experienced something similar with the Galaxy F23? Could this be caused by a swollen battery or could it simply be an issue with the back cover/adhesive becoming loose?

I’m mainly looking for advice on what I should check and whether it is safe to continue using the phone. Should I stop charging or using it until the battery is inspected?