Traefik-forward-auth with baseurl/pathprefix


I have a number of services running with using the pathprefix feature.
But as the Basic-Auth is excellent for a beginner I want to make my system a bit more convenient and want to deploy oauth using the traefik forward container and google.

Unfortunately is the documentation really not that easy to understand for me at this point.
At the moment I get redirected to google but afterwards I end up with the stripped prefix url.
So im asking this way for help does anybody maybe got already in touch with this topic.