That's really awful. I haven't gotten around to playing your game yet, though I've had my eye on it for a long time. It's really interesting! I'll admit I wasn't sure if it had non-sexual adult content or not, since I chanced upon it while looking for adult games, and it sounds pretty clear after reading this that it doesn't. That's fine; it's still interesting, but given the situation I thought I should mention that misunderstanding, in case it's useful.
Overall I really wonder what ever happened with Itch.io. When the big payment processor mess happened, I thought they'd sort things out, and then it didn't happen. But, it's only gotten weirder since then. Deindexing and blocking non-adult games with LGBT content, allowing lots of adult games to still be soldagainst the rules of their site and payment processors... It's not right to go half way in and out like that. If they're going to take a stand and defy the payment procesors and take money for adult games, they should do it for all of them.
Of course, as you said, they have no way to actually verify if a game is adult or not, or any other factor of the content. They don't have the staff for it. They could try something like depending on user reports to let them know if a game is adult, there's lots of prudes who would report all the things, but if the payment processors really cared itwould be too late anyways; they're already violating the rules and taking money for adult games. But, if the payment processors don't actually care, why is this all still going on?
It's so bizarre.
All in all, again, sympathies on this wretched situation. I hope that you keep making games, finding success, and a welcoming audience for your work.