The problem here is that Microsoft has interests now on GitHub, same as Nvidia has interest on ARM. Sure they will assure blablabla bla bla... seriously, do not even try to denny interest on expensive acquired stuff
Gitlab wouldn't fix the problem here - if Gitlab were owned by Microsoft, even if fully FOSS, Microsoft would probably do the same thing.
The problem here is that Microsoft has plenty of interests, and protecting Github's sanctity is not #1 on that list.
IMO this is the problem with FOSS services running on a corporate of under base. We aren't their main source of money, so they have perverse incentives.