It seems random to you because you get the order wrong. The links don't appear below comments, but above them. They are broken avatar images which are hyperlinks to a user's profile just like their username.
The avatars should be displayed next to usernames, but since several days ago the code has had a problem and lifts the avatars above the respective comment boxes.
Oh my god. How could I miss something that obvious? Wow. I'm embarrassed right now.