This situation is normal. Apple's warranty stipulates that if the battery storage capacity of Apple's mobile phone is only 80% or less within the one-year warranty period or the warranty scope of AppleCare plan, you can go to the Apple Store or an Apple authorized service provider to replace the Apple battery for free. The loss rate of the battery is also related to the usual usage habits.
Apple's battery is healthy and 90% normal, indicating that the battery life is lost, but the battery life does not affect the use and can be replaced. The design life of apple battery is generally around 500 cycles. After one year, the mobile phone will have obvious battery loss, and the battery health is generally between 80% and 90%.