iOS 14.2 update

Did you restart the device after the upgrade? You might also try a Forced Restart...

Force restart iPhone - Apple Support

You can also try deleting Apple Books app and re-download the app back:

Delete a built-in app from your device

1. On your iOS or iPadOS device, touch and hold the app.
2. Tap Rearrange Apps.
3. Tap  in the upper-left corner to delete the app.
4. Tap Delete. Then on an iPhone X or later, tap Done. Or on an iPhone 8 or earlier, press the Home button.

If you have an Apple Watch, deleting an app from your iPhone also deletes that app from your Apple Watch.

Restore a built-in app that you deleted

1. On your iOS or iPadOS device, go to the App Store.
2. Search for the app. Make sure that you use the exact name of the app. Find the correct name of built-in apps.
3. Tap  to restore the app.
4. Wait for the app to restore, then open it from your Home screen.

If you have an Apple Watch, restoring an app to your iPhone also restores that app to your Apple Watch.

With iPadOS 14.2, everything including the Books app are working fine here.

I don't think there's a iPadOS bug with Books app,

try troubleshooting with Restart and or Force restart iPad => Restart iPad - Apple Support

I’m on my iPad now waiting for the other shoe to drop. 14.2 is the biggest piece of crap Apple has ever put out. My iPhone 10 decides what I need to do for it-not the other way around. Every day I have to restart it 3 or 4 times and I still get the no access to cellular network crap. Apple has always been THE system that you could depend on to be stable. Now it’s worse than Windows Millenium—haven’t heard of it? Didn’t stay around long but I had it or rather it had me. Apple is becoming the new Microsoft-God help us.

FWIW: My 2 iPad Pro 3rd generation are running fine with iPadOS 14.2.

This is a user forum and that's all I can think of to suggest. So now I will direct you to Apple. To contact Apple directly, please click on Contact Support at upper right corner of any forum page.