Recover old authenticator

Hi, I’ve set up Microsoft Authenticator on a new iPhone. When I log in, I only see my Microsoft account. I previously had my Facebook account in the app, but it’s no longer shown.

My old iPhone was lost and not backed up to iCloud. Now I can’t log in to my Facebook account, which I use for work, and it’s urgent.

Facebook requires Microsoft Authenticator for two-factor authentication, but the account is missing from my app.

Does anyone know how I can restore my Facebook 2FA in Microsoft Authenticator?

Thanks in advance.