As far as I know, itch.io doesn't take into account what you search for and look at when displaying results, it's the same for everyone - and I applaud them for this. If they did otherwise, I'd just ignore my account here, and only ever use the site while logged out.
So it's not you, it's just a matter of... lots of people are making small horror games and putting them on twitch. No idea why, it's kinda been an ongoing thing on the site for a while now. It seems to mostly come in waves at least? Same with twine engine text games and visual novels, though at least there the reason is obvious: they are relatively easy to make compared to other sorts of games. Horror game or visual novel or whatever else, nothing wrong with making and posting these, depending on my mood maybe I'll even check them out at some point. The real question is: Why the hell are we STILL unable to filter these out!? We have been asking constantly for YEARS, it's like the single most requested thing for the site and yet nothing is ever done with it...