Comment by amiga386

That's the collective choice of the authors of those packages. A go module path is literally just the canonical URL where you can download the module.

The golang modules core to the language are hosted at golang.org

Module authors have always been free to have their own prefix rather than github.com, even if they host their module on Github. If they say their module is example.com/foo and then set their webserver to respond to https://example.com/foo?go-get=1 with <meta name="go-import" content="example.com/foo mod https://github.com/the_real_repository/foo"> then they will leave no hint that it's really hosted at github, and they could host it somewhere else in future (including at https://example.com directly if they want)

https://go.dev/ref/mod#vcs

Another feature is that go uses a default proxy, https://proxy.golang.org/, if you don't set one yourself. This means that Google, who control that proxy, can choose to make a request for a package like github.com/foo/bar go to some place else, if for whatever reason Microsoft won't honour it any more.