First, perhaps understand the Apple Support Community is a user-to-user technical forum. Contributors here are all end-users, just like you. Other than the site Moderators, Apple neither monitor nor participate here.
As such, if you hope to reach Apple through these forums, you will be disappointed.
The behaviour that you describe is entirely normal. The displayed battery charge percentage is effectively an estimate based upon battery voltage which can vary - in particular when restarting an iPad. The restart process is CPU intensive, increasing load and reducing the instantaneous battery voltage.
If you have any concerns, you would be best advised to contact seek Apple Support and request a remote diagnostic test of your iPad. You can contact the Support Team using the Support link at top-right or bottom-left of this page.
Alternatively you can initiate and manage your support cases using the excellent Apple Support App. If not already installed on your iPad, the App can be downloaded from the App Store:
https://apps.apple.com/app/apple-support/id1130498044
You might also visit the Genius Bar at your local Apple Store or Apple Authorised Service Provider (AASP) - where the technicians will be able to hands-on test and assess your iPad. If a fault is identified, you'll be in the best possible place to explore your available options:
Genius Bar Reservation and Apple Support Options - Apple