Battery warranty

Perfectly normal.

Batteries degrade over time with usage due to chemical aging, that's just how they work.

You can expect about a 1% drop per month with average use on an iPhone.

Apple recommends replacing it when it reaches 80%. To check your battery health, go to Settings > Battery > Battery Health.

iPhone Battery Replacement.

iPhone Battery Repair & Replacement - Apple Support

About Lithium Ion Batteries

iPhone Battery and Performance - Apple Support (IN)

Here are some tips on maximizing battery life.

Batteries - Maximizing Performance - Apple Batteries - Maximizing Performance - Apple

That does not change the fact that is perfectly normal and expected for Battery Health to decline at an average rate of about 1% a month.

But, you can certainly make an appointment at the Apple Store or take the phone to an authorized Apple service shop if you want to have them confirm that your battery is operating normally and just fine.

You can find a list of authorized service shops in your area using this link......Find Locations

This never happened before with all my iPhones in the past.

In particular after the IOS 17x.