[bloak]

You can set your own default for new repositories: (circular picture in top right corner) -> Settings -> (about half way down on the left) Repositories -> (top of page) Repository default branch

I don't know whether changing that changes the "new repo text" but since the text for "Repository default branch" says "You might want to change the default name due to different workflows, or because your integrations still require “master” as the default branch name." I would guess the default default is "main", so either you have set your default to "master", or the new repo text is out-of-date, I would guess.