Hi there Mayokun17,
We understand you have a question regarding the battery health on your iPhone, and we'd like to share a resource that can help.
Check it out here: iPhone Battery and Performance
Specifically, take a look at the section below:
"Your battery's maximum capacity
The Battery Health screen includes information on maximum battery capacity and peak performance capability.
Maximum battery capacity measures the device battery capacity relative to when it was new. A battery will have lower capacity as the battery chemically ages which may result in fewer hours of usage between charges. Depending upon the length of time between when the iPhone was made and when it is activated, your battery capacity may show as slightly less than 100%.
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. Learn more about charge cycles."
Regards.