Luckily, Git is decentralized, so that shouldn't be an issue.
Wouldn’t it be wonderful if when GitHub is down we could just move to a different GitHub instance? Isn’t it sad that we can’t, although it would be very feasible technologically?
This is a problem to work on, but it's not a Git problem.
Ain't it cloud scale? Have you tried moving it to serverless?
At this point, it seems that GitHub is even more unreliable than a self-hosted solution.