Itch.io has some sort of automod monitoring every post, and I believe I read somewhere that it learns what should be hidden through our reports. If that's true, it doesn't work very well. It has never caught actual spam.
In any case, it almost only hides posts from new members, but doesn't tell me about it, so I have to check the "pending posts" section from time to time and manually approve posts from new members.
"A new post or topic may be placed in the pending queue if it is flagged by the spam detector, or by the moderation settings of the community. Posts here will not be visible to others until approved by a moderator."
I am not aware of any "moderation settings of the community" besides allowing comments, but that's what it tells me.