[samename]

Key highlight:

> 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

[kjeetgill]

To add emphasis to this: they changed the default branch name for new repositories.

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.