The Vim plugin communities are notorious about the GitHub bias too with almost everything just assuming GitHub.

npm is supports shorthands for some Git forges (though no SourceHut or Codeberg), but without the `forge:` syntax, you get GitHub as the default which is also favoritism (no surprise with Microsoft owning GitHub and npm though).

The worst offender IMO though is Elm who ties their entire package management ecosystem to GitHub where both your identity and the ability to upload a package requires a GitHub account and hosting must be there too, and downloading requires that GitHub's servers are actually up (with the community needing hacks to deal with the non-so-uncommon likelihood of GitHub being down and no way to point to a mirror).