Here is how to Clear Other storage on your iPhone or iPad - Apple Support and with a fix that arrived with 13.6.1.
You may have to use a computer to update to 13.6.1 or later (13.7 is current):
Update your iPhone, iPad, or iPod touch - Apple Support
Failing the above sequences, back up, reset, reload iPadOS 13.7, and restore your backup.
Per Apple, Other: Non-removable mobile assets, like Siri voices, fonts, dictionaries, non-removable logs and caches, Spotlight index, and system data, such as Keychain and CloudKit Database. Cached files can't be deleted by the system.