iPhone 8 Plus literally heats up every time

My iPhone 8 Plus just suddenly decided to be broken. It was literally just fine, it could even last a whole day without charging until one night, it just decided to drain its battery very, very fast. It literally went from lasting a whole day to lasting only for 3 hours in just one night. And right now, it heats up even the slightest usage, like I would just check the time and a few clicks around the phone and it’s already warm as if you’ve played a hardcore game on it for a short period of time. Battery Health is still at 97% and I’ve already done every possible battery saving tips I could find on the internet, even bought a brand new charger and removed the thick case.

By the way, it heats up on that specific part of the phone just below the dual camera, based on the pictures on the internet, it’s where the main circuit board is located. The battery itself rarely even heats up. I don’t even know what to do now.