iPhone 8 Drains Fast and Battery Overheats When Charging

I saw a listing for a really cheap but defective iPhone 8. The seller says that the phone drains really fast and that it overheats when it’s charging. The seller also sent a photo of the battery health, stating that the maximum capacity is at 94% and that the battery is currently supporting normal peak performance.

Is the problem from the battery possibly being defective or is it a more complicated issue, such as a logic board problem? Thanks to anyone who will answer!