You know you could actually use a self-hosted GitLab for your team's projects. Which is why projects like Xfce [0], GNOME, etc are still up and running and don't suffer from this. Also if I were a school sys-admin I would self-host and use GitLab. [0] https://mail.xfce.org/pipermail/xfce4-dev/2020-April/032436....
And there are some good reasons for not self-hosting: price/comfort, built-in tools, decent security without having to do your own, etc.