I restored an iPhone 12 from my iCloud backup. I then tried to login to Lastpass with my username and password. It then asks for an MFA code from Authenticator. I open Authenticator and in order to restore the backup it asks me to login to Lastpass which then asks me for an MFA code, etc.
Sorry in case its not clear. When I open the Authenticator app it needs me to login to Lastpass in order to recover its own backup. However, Lastpass needs Authenticator to login. I hope thats more clear. Thanks.