They're largely changes dictated by payment providers, namely Visa and Mastercard. Unfortunately, as they control most of the worlds payment systems, they can throw their weight around and dictate whatever draconian puritanical nonsense they see fit because no sufficiently large platform would be stupid enough to refuse - the consequences of doing so would likely be bankruptcy.
Patreon has some blame here too, their communication and transparency has been utterly dogshit and there's practically no support or recourse for those affected, but I'm certain they wouldn't be adhering to these policies if their hands weren't forced - it's no doubt terrible for their business. Visa and Mastercard are the real bad guys here. And Patreon's hostility towards 18+ content won't improve unless Visa and Mastercard decide (or are forced) to reverse course which almost certainly isn't going to happen. Other platforms like Subscribestar are affected as well, but the largest platforms are obviously impacted the most.