Battery health
The battery health has decreased due to using the phone too much while playing while it is plugged in
Question marked as
"A normal battery is designed to retain up to 80% of its original capacity at 500 complete charge cycles when operating under normal conditions. The one-year warranty includes service coverage for a defective battery. If it is out of warranty, Apple offers battery service for a charge." --> iPhone Battery Repair & Replacement - Apple Support
