This is also normal. The more times you charge, the performance of the battery will definitely decline. If the battery health drops to 89%, it means that the battery has begun to age. If it is lower than 80, it is recommended to replace it. According to Apple's official statement, after 500 charge and discharge cycles, the power of the iPhone will not be less than 80%. Suggestions for battery use:
1, try not to play games while charging.
Don't wait for the battery to run out before recharging.
3. Don't leave the phone in a charging state for a long time, and unplug the charger in time after charging to 100%.