I have an app using Firebase Authentication with Sign in with Apple as an option. When users download my app on a new device and want to log in again, I need to know if their Apple ID (or private Apple ID) is already associated with an account.
My app uses anonymous accounts by default with the option to link to a different provider later. But with Sign in with Apple, if I attempt to link the credential, the credential is burnt.
Is there any way I can tell if the credential I receive from Sign in with Apple is a new one or an old one?
I tried to extract the email from the JWT so I could see if an account already exists, but Firebase are removing the ability to query accounts by email on the client side.
I feel like I must be missing something obvious so help is appreciated!
