Hello friends. I am on the infrastructure team at Docker. We are fixing this. I am sorry you all have run into this bug!
From what we have seen, this only happens for dual-stack networks where customers are running docker-in-docker.
We found that after the release of IPv6 for Docker Hub registry endpoints, some assumptions made in our system were no longer valid since all of the major endpoints were now dual-stack. This is why you are being forced to reach auth.ipv6.docker.com.
Another option is to enable IPv6 for Docker containers since the problem is with using IPv6 from within a Docker container. The host machine can reach the proper endpoints fine, from what we have seen.
We are working on a fix right now.
@itsreddi do you mean self-hosted runners or runners hosted by GitHub? Could you share relevant parts of your GitHub Actions workflow?