It is information provided to the instance runners, mods, and other fedeverse platforms such as mastodon. It inherently tracks such to know if a user has previously liked/up voted an entry.

So you may have a conversation on here, and some users will know who is downvoting, some will only know who's upcoming, and some will know none

It will also strengthen the hive mind, exponentially.

I think part of the motive is to make brigading harder (show if users or bots are colluding to vote things up or down)