During the warranty period, the maximum battery capacity has dropped below 80% of the original capacity, and Apple will help you replace the battery for free.
If a batch of iPhone batteries are defective, Apple will also release a corresponding free replacement plan;
When repairing and replacing the battery, it should be noted that if your iPhone is damaged, such as the broken screen, you need to solve these related problems before replacing the battery, which may lead to additional maintenance costs;
To check the battery health, you can go to the Settings-Battery-Battery Health page under iOS 15 version, which can be seen in the Maximum Capacity option.