I have never once in my life cared about where a programming language kept its source and I think if anyone is using that as a basis for decision-making, they are truly a moron.
I don't care if it's on GitHub at all, it's not hard to work with any arbitrary git remote. CVS would be a weird choice, but it wouldn't be a dealbreaker on its own. Fossil or some other modern alternative VCS wouldn't be a red flag or weird at all.
But I wasn't talking about contributing to the language, which is a weird standard to use here since Zig isn't interested in outside contributors. I was talking about choosing a programming language for use for some professional or personal project. I don't give a fig what version control solutions the team chooses to use if the language is good and solves my problems, and I would consider it very strange if someone tried to argue that I shouldn't use some language because they put their code on a non-Microsoft owned server.
I generally agree with you that choosing something based on where it's hosted is dumb. I still think there could be an impact wrt a network effect.
The original comment you replied to was talking about "the loss of network effect" and you sounded dismissive of it. It might not even matter, but I think it's somewhat fair to say it could have an impact.
I agree. It's possible in the future a project hosted on codeberg is a silent "stamp of quality". Though, I still think there could be impact wrt a network effect.