I'd point out that if you look at issue 5439 the team itself was originally unaware of the high number of edge case states of the merge request and closed the issue prematurely. Having many code paths is a code smell so I'd suggest simplifying your UX and edge cases here.

Since you own the merge request flow, I would suggest looking at the page and all it's edge cases and seeing where you can simplify for the user. There is a dizzying large amount of info and CTAs presented to the user; it's pure information overload. Don't just measure yourself by how many features you ship but rather on how you communicate those features to your users. Simplicity is a powerful feature in itself.

Looking forward to batch comments.

The disapprove merge request is a feature available in Phabricator and other competitors so I would look to see how they've implemented it.