Does anyone know what’s happening at GitHub?

Microsoft has a lightweight "code storage" platform - GitHub and a heavyweight "code storage" platform - Azure DevOps. I see them unifying in the future, ideally taking the good from both platforms, but very likely in a way that allows the company to optimize cost, whatever that means. Either there was no need for a CEO/COO at GitHub, or they were not the best to make this transition, or they didn't agree to the direction in which GitHub is going.

I dont know. But I think it is quite normal during these sort of transition. Because if she was a CEO candidate and she lost may be its better to leave than to stick around. So probably just some power play. Not a change in strategic direction.

Looks like it's little more than corporate churn to me. Dotnet has been a bit of a clusterfsck for the past few years, I can imagine anyone with their name associated with it being in the hot-seat so to speak, especially working at a website that for the most part sustains open source development.

Why do you care? It's not like GitHub is going to be any different. It will still continue to host your code.