Ah, that's strange! I wonder why that might be?
https://itch.io/games?exclude=tg.horror
This link for example, shows everything for me except horror titles, with no other filters or tags needed or used. Does it not do the same for you?
It has been a while since I’ve actually tried to find something for myself, so it took me a while to realize: Those sets of result do show different games for me. Up until now I just assumed the default order was kind of randomized, because both the exclusion filter you linked and the default display of games display “311,173 results”.
… I take it that number is capped at 311,173 to show some mercy to the servers and that itch.io hosts more than 311,173 games then? ;) x)
Thank you for your help, FrostWorks! This has been both educational and fun for me. :)