Hi @MartinHerbener,

A person's account isn't really "based on" a particular type of authentication, unless the login is specifically associated with a particular provider when the account is created via SIS (as shown by the "authentication_provider_id" value under users.csv in https://canvas.instructure.com/doc/api/file.sis_csv.html).  

If the login is associated with a specific authentication provider, you will be able to see that information in the Provisioning Report (Settings > Reports), but not via the GUI.

However, if the login is not associated with a specific auth provider, then the user can login using any of the authentication providers, as long as they have working credentials in that auth provider, and the login_id that the auth provider passes on to Canvas after the user has successfully authenticated matched the Canvas login_id.