> Any massive infra migration is going to cause issues.

What? No, no it's not. The entire discipline of Infrastructure and Systems engineering are dedicated to doing these sorts of things. There are well-worn paths to making stable changes. I've done a dozen massive infrastructure migrations, some at companies bigger than Github, and I've never once come close to this sort of instability.

This is a botched infrastructure migration, onto a frankly inferior platform, not something that just happens to everyone.