It's probably not Subscribestar specifically, payment processors are adding all sorts of new restrictions on funding adult entertainment over the past years. My updates always go free for public access after a month or two, so you won't miss out, but it's very unfortunate that this problem exists.
Thank you for your response and interest. I think I'll try virtual card platforms like Wise or KAST. I can say you're one of my favorite content creators, so I intend to support you.