Recovery Code is being introduced to assist with two-factor authentication (2FA) in the event a user is unable to receive their 2FA code via Authentication App or Mobile SMS. Users who enable 2FA from now on will be presented with a Recovery Code that they can use for any 2FA verification step. Once a Recovery Code has been used, a new one will be generated.
For more information: Set up Two-Factor Authentication (2FA) AU | UK | MY | NZ | SG