Backup restore with 2FA - something went wrong at login

Hello everybody,

I have 2FA enabled since a long time.
Yesterday I set up DuckDNS and HTTPS and I’ve discovered my camera integration is not working anymore (stream error). I wanted to restore a previous backup to check if this was because of my changes or to something different.
I tried to restore a backup from a couple of days ago and everything seemed to work properly. I was presented with the login screen and I entered my username and pwd. But at the moment I should have seen the 2FA field I got the error “something went wrong” (or similar - I do not have the interface in ENG). No way to proceed further.

Luckily I was still logged on my mobile so I could revert to the latest backup.
After the restore to the latest one I could log from the computer where I was receiving the error message (2FA field was correctly displayed).

I thought something went wrong with the restore or maybe the backup was corrupted; so I tried with a different backup. Same problem and I could solve using the same workaround.

Before I do it again… can anybody shed a bit of light on this odd behavior?
Especially because I have the feeling that any backup I have is pretty useless if I do not understand what is going on and I’d like to discover it before I really need to restore any.

Thanks a ton to anybody who can help.