After going over the steps in the docs for setting up google authentication I kept getting errors saying "This domain is not authorized for OAuth operations for your Firebase project". Some debugging in the browser and I see the actual domain needed is ff-debug-service-frontend-ygxkweukma-uc.a.run.app . I added this to my Firebase settings under Authentication -> Settings -> Authorized Domains and it worked.
Leaving this here as a note for others with similar problems.