Ok, I have a work account on Gmail. Having the experience of being locked out of Gmail previously (endless loop of "You are entering the correct password but we're not sure that it is you, try again later"), I created a 2fa via Google Authenticator and set up Backup Codes and thought I'm safe from them asking me to sign in on another device or enter sms code (I don't carry that phone with me).
So, one sunny day I decided to add standard iOS mail app to this account, and lo, an hour after connection I get a message, that due to strange activity on my account, I need to enter code sent via sms.
Ok, I don't have that phone with me, so I try to log in with Authenticator, and no, no good: 'we are not sure that it is you, enter code sent to sms'. Ok, I dig backup codes, enter them, and still get 'we are not sure what it is you' message.
What's even the point of allowing to set up Authenticator or Backup Codes if they don't do anything?
If there are some people from Google reading this, please, don't reach out to me offering to help. Just change this dumb system.