Their infrastructure tracker has a lot of interesting info about the move[0]. You can also read through the development mailing list, it has a lot of discussion about the GitLab migration.

At GitLab we're tracking the blocking issues they've brought up in this issue[2].

[0]: https://gitlab.gnome.org/GNOME/Infrastructure/issues [1]: https://mail.gnome.org/archives/desktop-devel-list/ [2]: https://gitlab.com/gitlab-org/gitlab-ce/issues/35287