If I comment on a comment that was upvoted up to the top, I am also then bumped up to the top. I often struggle to find the second comment to an article because the first comment is full of comments to that comment and comments to the comments of that comment. Especially on mobile I find myself scrolling up and down until I find the second most upvoted comment..
Well, I don’t think there is any question about it. It can only be attributable to human error. This sort of thing has cropped up before, and it has always been due to human error.