As others have pointed out, this is Gitlab. When it comes to github, they previously helped me transitioning a bugzilla into github issues, but it doesn't look like they do this anymore.

Back then, I managed to get approval from all our contributors/issue authors so that their individual bugs and comments would show up as their individual bugs and comments, as well as retaining issue numbers.

This is the code for it, if anyone is interested, but as I said the whole thing is unsupported now: https://github.com/jleclanche/bugzilla-to-github

There's an unofficial issue import API:

https://gist.github.com/jonmagic/5282384165e0f86ef105

But it doesn't let you change ownership of issues or comments; everything appears as created by the importing user.

That makes sense. You shouldn't normally be allowed to impersonate another username, which is exactly what a full import does.

Repository owner can edit comments arbitrarily, which already allows for impersonation, although to a lesser extent.

Also, you can impersonate commits freely.

I don't think allowing full import would be a big deal, especially if the UI made it clear that the comments were imported.

With full comment edit history that's no longer the case as much, although you can delete the diffs.

That's the one Github staff helped me use (though there were no public endpoints at the time). I recognize some of this. I don't think it's supported anymore.

Likewise mine for Cyrus:

https://github.com/cyrusimap/BugzillaImport

They moved from bugzilla to GitLab (not GitHub)

Which one? V3 or V4?