Battery health

Click on this link about Phone battery and performance to read about the battery health feature and what is considered normal performance --> iPhone Battery and Performance - Apple Support

"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." A degraded battery may display the notice: "Your battery’s health is significantly degraded. An Apple Authorized Service Provider can replace the battery to restore full performance and capacity." If it is not at or above 80% "normal", consider contacting Apple about a battery replacement. --> iPhone Battery Repair & Replacement - Apple Support

What you are seeing is nothing unusual.

Hey there,

That’s normal, All rechargeable batteries are consumables and have a limited lifespan — eventually their capacity and performance decline so that they need to be replaced.

Apple recommend to change the battery if it becomes 80%or less.

For more info ☞ About the battery and performance of iPhone 11 and later - Apple Support

My battery health reduced in only 24 days using 100% to 99%

Normal. Battery Heath will decline an average of about .8% to 1% a month. That's an average. Some months it might not decline at all, then decline 2% the next month.

After 12 months, your Battery Health will be about 88-90%

After 24 months, your Battery Health will be about 80-82%.

Stop worrying about the battery and plan to replace the battery when the Health is at 80%

Is there any replacement policy.

No. Please read what I wrote above again.

It is normal for Battery Health to decline an average of about 1% a month.

If the battery declines to 80% under the original one year AppleCare warranty, Apple will likely replace the battery.

Using 14 Plus , which is most battery compatible handset, battery Health Reduced to 99% with in a month .’ Is there any replacement policy.