Setting aside how weary I am of "M$" (it's just about tied with using "sheep" to describe Apple users), what on God's green earth does Microsoft have to do with the OP's point? GitHub itself is not and was never open source. It's not like Microsoft bought it and closed off the source. Do you think using Microsoft tools demonically injects anti-FSF sentiment into your work? ("I started using VS Code, and now whenever I try to work on GPL 3 software, my keyboard becomes too hot to touch until I close the window!")

Personally, I have a different take than the OP, although I'm not sure this is really a disagreement. I would argue open data formats are more important in this context. If I write text in Markdown, it doesn't matter whether I'm using Emacs or a closed-source, proprietary commercial editor; the text isn't tied in any meaningful way to the editor. Likewise, a Git repository hosted on GitHub isn't tied in any meaningful way to GitHub. It's... a git repo.

As long as GitHub isn't doing anything that I particularly object to -- and "oh woe, it is owned by Microsoft" is not an objection I share -- there's a pretty good case for continuing to use it. I'm taking a calculated risk that it's both unlikely to go away anytime soon and to markedly change business direction in an unfriendly way, but if it does? As long as my local copy is up to date, I can re-publish it anywhere and just, well, stop using GitHub.

Not really, "free/opensource/selfhosted/alternative" [0] as in "here this minio bucket that behaves like S3 but you can play with it without an amazon bill of death that may or may not be coming".

[0] Also, thanksnotreally for cherry-picking and putting words in my mouth with your use of `!M$`, screw you too.