Yesterday, I first heard of the screwed-o-meter:
https://rachelbythebay.com/fun/som/
Plugging in for GitHub gets a score of about 90%. GitLab is in the mid 30%'s. (Assuming Arch is keeping a backup mirror of the bugtracker, etc on a private instance somewhere.)
That seems good enough to not bother with actually hosting it yourself. I'd rather they spend volunteer time on stuff other than applying security patches to a giant beast of a web service.