On mobile, on certain user profiles, there's a little comment-upvote type arrow. I tapped it repeatedly(since tapping comment upvotes on mobile doesn't always work--you miss at times) just to see what it does, and it wouldn't work.
Doing some investigation on desktop, I realized that it's not supposed to do anything. More investigation revealed that it was part of the of the user bio (and shows up as a plain arrow when the bio is empty):
Sort of inconsequential, but this could be improved to be less confusing.
Though this probably will be declined since it complicates mobile site code :/