CC processing business is hold by 2 American companies. When they warn you (through your CC acquirer), you have zero negotiation power. Comply or die.

You can use proxies if you are a small company. But at onlyFans' level, the solutions are limited.

PS: By experience, I can also confirm that most of the CC acquirers evaluate your business not on its legality but on its morality.

PS2: With mandatory 3DS2, the excuse of high fraud/complains rates (which were true 10 years ago) does not make sense anymore.