Yes this is probably it. The biggest flaw in the code. I will note, only one person pointed this out in the entire thread and that's you.

If there's any raw legitimate claim to a rejection it's this.

Literally everyone else commented on a bunch of superficial things and no one hit on the extra zrank here. It's not even about not being able to follow the code. I think very few people even remember specific redis commands or even bothered to follow the logic.