Having used multiple code review tools (Gerrit, Phabricator), GitHub's code review is frankly one of the worst UX's for humans to use for this purpose (go try to review a rebased patchset, or have to wade through the inefficient use of space in the UI), so I'm not surprised AI has trouble with it as well.
In exploring `gh` CLI extensions recently I found at least 2 devoted to being a better PR review interface. I've also seen [Trag](https://usetrag.com/) and others pop up.