This question already has an answer here:
That's the response I got to a flag I raised about a
git question which had already been answered on StackOverflow a few years earlier.
Git runs on Ubuntu as well as on Windows or Mac, so it could be asked on AskDifferent or SuperUser, but I doubt it would be welcome there more than on SO.
Anyway, if we really allow questions about "any tool that runs on Ubuntu", that's opening a can of worms. People could ask questions about, I don't know, Slack, because it has an app that runs on Ubuntu.