Bottom line - iPadOS 14.7 has not yet been released by Apple as a production version. Whilst the production release is perhaps imminent, anything released to date will be a beta version.
You would be well advised to delete the failed update from your iPad.
Settings > General > iPad Storage - Scroll down the list of Applications until you find the Apple Update - then tap and select Delete Update.
Be aware that if you have a beta-profile installed on your iPad, installation of production software will be inhibited. If you are currently enrolled in a beta programme and wish to return to using the current production version, this support page provides the necessary information to remove the beta from your iPad:
How to uninstall iOS beta software - Apple Support
Beyond this, the Terms of Use that govern participation within these Support Communities preclude additional advice or guidance in regard to beta programmes being given here.