iPad - All Notes are missing after software upgrade to iPadOS 17.2

See >>> Delete and recover notes on iCloud.com - Apple Support

If your Notes were synchronised with iCloud Notes, they should be recoverable if accidentally deleted. If instead you were not using iCloud Notes, your Notes should have been included within your iCloud or iTunes backup.

However, be aware that iCloud backups are incremental. If your iCloud backup has been refreshed since the Notes were deleted, the deleted Notes will also have been removed from the iCloud backup - and will be unrecoverable.

Restore your iPhone, iPad or iPod touch from a backup – Apple Support

Did you get any answers about this issue? I just had the same thing happen to me!