When multiple people are replying to a comment, the order of the replies is bizarre. I described it in more detail three years ago when starting this community thread: https://community.adobe.com/t5/acrobat-discussions/show-comment-replies-in-ascending-date-order/m-p/15039678

I can't imagine any reason to have the replies in any order other that chronological (oldest first, so it can be read like a conversation), but if there is, then at least allow an option (in Preferences perhaps) to choose between chronological and what it does now. (Note: This problem happens in both Acrobat Pro and Adobe Reader - I'm requesting the fix for both.)