It's because the owner of this site made an announcement the week of the great eroge slaughter that if you put no payments, you will be indexed again, and that all paid NSFW content will be auto deindexed.
https://itch.io/t/5149036/reindexing-adult-nsfw-content
However I and many others have done that and we are still de-indexed which I guess means we're still on Itch's shit list. But they won't tell us what we're doing wrong.