Implement backup/recovery option for Google Authenticator
There's no backup/recovery option implemented. Users can lose/change mobile phones. Google Authenticator don't
have any standard procedure to recover.
If it is not possible,
add a big fat note warning that users should take a screenshot and print out the page (and store it at a safe place)
Yeah, this is a pretty standard feature of 2FA, Idk why this was omitted when the Plesk implementation was written...