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< Feedback on ppixiv for Pixiv
It's hard to implement filters like that client-side without causing problems. (For example, if you viewed recommendations with followed users hidden, and recommendations that Pixiv gave were 90% people you're following, we might accidentally start loading 10x as many pages trying to fill the screen, which might spam the site.) I think that info also isn't included with search APIs. These sort of filters really want to be done on Pixiv's side, but unfortunately they don't seem to be interested in expanding search features...
The closest thing I know to do that particular sort of search is "Recommended users", which shouldn't return users you're already following (of course that doesn't give you any flexibility about what sort of content you're looking for).
i love this pixiv extension but there is one feature i think would be great if its possible to be able to hide people you are following when looking at posts to easier find new people and the like