Cannot add Apple recovery key
iPhone XR, iOS 14.2
To add a recovery key to your Apple account, you must record the provided recovery key, then enter it again to confirm that you have recorded it. In some cases, however, even if you verify the recovery key correctly (i.e., enter the exact recovery key provided) Settings.app may complain that you didn't:
Your recovery key is incorrect
Sign out of iCloud, restart your phone, then sign into iCloud again.