https://outrungaming.com/mastercard-addresses-nsfw-game-censorship-statement/
Payment processors got petitioned (from an anti-porn group) to ban games with rape, incest, and sexual violence*, and it went from there. Steam and itch couldn’t tell which games had the suspected content in them iirc, steam delisted in batches while itch had to manually review everything. Public perception played a factor in why the payment processors acted the way they did. Then you had the backlash to the treats being taken away, even gog gave away some nsfw games (but none of them had rape, incest, or sexual violence so weren’t being currently boycotted). Now it’s harder to get a nsfw game approved on steam. Also this anti-porn group has gotten other games like rape simulators (No Mercy) delisted before. So they had experience.
*I should have also noted that CP was a part of it. I did not see that on steam but the other stuff was 100% in steam’s library.
The anti-porn group (CS) has had experience petitioning for things like this before. They usually petition the store (steam or itch) but were told to pound sand instead, so they went to payment processors. Keep in mind, Patreon has had a similar problem with nsfw work in general because of payment processors. These companies are ok with censoring adult work, iirc there was a provision for it. CS posted their letter on their website that they sent. Patreon blamed it on KOSA and project 2025.
https://www.patreon.com/outsiderartisan/posts/some-final-on-135199925