Pretty sure it’s just users that disagree going and downvoting latest comments. At least for me, there was a MAGAt that didn’t like anti-trump stuff and gave me 1 downvote on everything I posted from that single comment, on backwards in my history for about a week or so.

I thought it was a bot at first, but then I realized it started right after my comment replying to him correcting him on his conspiracy theory stupidity cult nonsense. Everything posted after that comment received no downvotes.