The title is an unfortunate mistake, it just goes to show GitHub’s dominance. Codeberg is free Git hosting. GitHub is a service, Git is the technology.
It could also say GitHub alternative because it provides things like issue tracking, static page hosting, release management, a UI for pull requests, Wiki and has a CI solution as well. Same category as GitLab and Bitbucket but ofc GitHub is the most popular of the bunch. Git alone is just a (useful) piece of that software forge puzzle.
I was puzzled by that too. I had some colleagues who did not even know they were two separate things…