auth/unauthorized-domain
what this Firebase error means
How it shows up
FirebaseError: Firebase: Error (auth/unauthorized-domain).
What it means
The domain the app is running on is not authorized for OAuth operations in this Firebase project, so sign-in with a provider such as Google is blocked there.
The usual cause in an AI-built app
The app was deployed to a domain, such as a vercel.app, netlify.app or custom domain, that was never added to the project's list of authorized domains.
Check this first
In the Firebase console, open the Authentication settings and check that the exact domain from your browser's address bar is in the Authorized domains list.