Sometimes App storage can be misreported - or may not fully tally with the total reported for a specific App.
Unless you are running short of available local storage - and have need to prune storage of unused files or data - you would be well advised to accept the inconsistency and focus on something more worthwhile. To be clear, I'm not dismissing your reported issue, but simply suggesting that iPadOS will sometimes uncover an inconsistency that cannot be easily identified and cleared.
However, if the inconsistency troubles you and the problem persists after performing a forced-restart of the iPad, there are other steps to try - beginning with a reset of your iPad settings...
While this reset will not cause any loss of data, as a precaution, it is always wise to ensure that you have a current iCloud or iTunes backup before performing the reset:
How to back up your iPhone, iPad, and iPod touch - Apple Support
When you are happy to proceed, you can perform the reset from iPad settings:
Settings > General > Transfer or Reset iPad > Reset > Reset All Settings
If the problem still doesn’t clear, the next step is to reset the iPad to factory settings:
Restore your iPhone, iPad, or iPod to factory settings - Apple Support
Otherwise, you would be best advised to seek assistance from Apple Support. You can contact the Support Team using the Support link at top-right or bottom-left of this page. Alternatively and perhaps easier, 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
