Is my 8 months old iPhone 13 Pro battery still under warranty?

In addition, if your battery health reaches 80% or below, Apple recommends you replace it. If you have AppleCare+, your battery will be replaced at no additional cost, otherwise $89 for your iPhone battery replacement.

Learn more ⇢ iPhone Battery Replacement - Apple Support

-Zachyy ✌️

Unless your phone sat in a warehouse for 18 months, the phone was not new when you purchased it.

Check your device purchase date and warranty coverage here:

Check Your Service and Support Coverage - Apple Support

What does it say?

Apple stopped making iPhone 13 Pros 2 years ago.

the phone you bought wasn’t new.