iPad Pro 12.9 seconds gen
How much is it to replace a battery on iPad Pro 2nd gen 12.9
iPad Pro, iPadOS 17
Question marked as
You can establish eligibility and cost of a battery replacement in your country/region here:
iPad Repair & Service - Apple Support
You might choose to visit the Genius Bar at your local Apple Store or Apple Authorised Service Provider (AASP) - where the technicians will be able to test and assess your iPad - prior to committing to a battery replacement or other repair:
Genius Bar Reservation and Apple Support Options - Apple