Most likely: Someone has taken exception to something you wrote and decided to go back and downvote a load of your old comments. It's a thing that happens. Victims complain about it from time to time. Eliezer says he's asked someone to look at the LW database for evidence of mass-downvoting but they haven't found anything useful; make of that what you will.

There are some grounds for thinking that people who make comments supporting (in rough terms) feminist views, and more generally but also more weakly "non-Reactionary" views, are particularly likely to attract the attention of mass-downvoters. (One might respond to this by avoiding such comments, or by defiantly making more of them.)

Less likely but not impossible: Someone has disliked something you wrote, gone back through your comment history, independently assessed the quality of each comment, and happens to have found ~25 comments that they think deserved downvoting on their own (de)merits.

[EDITED to add: Hello, downvoters! If you think something is bad about the above, please do let me know what. Otherwise, my working hypothesis is that the downvotes on this comment come from mass-downvoters who don't like being talked about. and I'll adopt my usual heuristic of responding to what look like mass-downvotes by posting more.]