> While I'm not forgetting the spirit of what Git is, I'm also remembering how GitHub used "all open repositories" to train their first Copilot without telling anyone.

As long as your code is out in the open anywhere the slop factories can train their models at it, regardless of whether it's on GitHub or your private server. So you might as well keep using GitHub at least as a gratis mirror. My reasoning is that if I'm going to be milked anyway I might as well freeload off GitHub.