@greg-wizards If that had happened with your Firefox or Chrome accounts, the result most probably would be the same. It would be a huge security issue if it were different.
Propably not, for example two-step verification in Google gives you, except Authenticator, alternative modes like SMS message, Voice verification and extra backup codes.
About Opera - therefore, it should either be possible to remove the e-mail address assigned to the account from the Opera database, which cannot be recovered or, after a certain period of inactivity, it should be returned to the pool of free addresses.
If any of these options are not possible, it means Opera is blocking e-mail addresses. The question for what? Because it's not for a security anymore. User protection should fulfill two roles - protection against unwanted access and protection of the user's interests. By blocking e-mail addresses the second role is not being properly realized by Opera. Obvious security flaw Guys...