Set the default branch for newly-created repositories
github.blog
github.blog
> On October 1, 2020, if you haven't changed the default branch for new repositories for your user, organization, or enterprise, it will automatically change from master to main. You can opt out of this change at any time
You can opt-out of this change of the default. I don't know why I'd read that as changing existing repositories unless opted out.
https://www.hanselman.com/blog/EasilyRenameYourGitDefaultBra...
Edit: oh I miss read. Thought this affected existing repos.
Opted in for new repos.