I've already signed the petition and emailed both visa and MasterCard (I have both). I suggest everyone does it and if you live in the Us, contact FinCEN and your representatives to support this bill
https://www.congress.gov/bill/119th-congress/senate-bill/401
Here's an email template:
Dear Visa Customer Service Team,
I am concerned customer about Visa’s recent efforts to censor adult content on prominent online game retailers, specifically the platforms Steam and Itch.io. As a long-time Visa customer, I see this as a massive overreach into controlling what entirely legal actions/purchases customers are allowed to put their money towards. Visa has no right to dictate my or other consumer’s behavior or to pressure free markets to comply with vague morally-grounded rules enforced by payment processing providers. Unless these draconian impositions are not reversed I will have no choice but to stop dealing with Visa and instead swap to competing companies not directly involved in censorship efforts, namely Discover and AmericanExpress.
Here's the link to a lot extensive thread: