“Initially derided as a GitHub clone…” I mean, let’s not kid ourselves, it still is. But so is Gogs/Gitea/Forgejo, Bitbucket, etc.
I appreciate that there are only so many ways you can do a web-based software forge, but most of the design cues and UX established by GitHub have been adopted by the other products in this space.
I’m not arguing whether this is a good or a bad thing—familiarity leads to productivity, of course—but in my opinion GitLab really does derive a lot of its success in being a “GitHub clone”.