Hi @tom.schreck,
Welcome to the Community!
Does this happen when you sign up using a database connection (provide an email and password on the login form)? Or does it only happen when you log in with Google (or another social connection)?
If it’s only with social connections, then it could be because the app is using Auth0 developer keys instead of your own Google developer OAuth credentials.
If that is the case, here are the docs for configuring a Google social connection: https://auth0.com/docs/connections/social/google