Avakian My understanding is that the pressure does not come from some religious right anti-porn fundamentalists (those Gilead folks are usually pretty comfortable with violence against women and would probably rather target gay porn) but more likely is the aftermath of some players in the porn industry not paying attention to the content they earn their money with, which was partly abusive and illegal and, most importantly, not acted. Mastercard and Visa cut their services to Pornhub after this was made public in the NY Times in 2020. Many people nowadays just won't accept such things anymore, even if in general they would have a liberal attitude towards porn. And incest is probably illegal in most countries.
As a result, payment providers are extra cautious and will not accept any porn content that is non-consensual or incest-related. It does not matter if this content is just acted, because the card companies for sure will not start evaluating videos or publicly defending the legal content produced by the porn industry.
Not sure though who drew the line between peeing and pee drinking. I am truly glad that peeing is still considered acceptable, because the urge really starts getting unbearable after a while...