You mean like this?
https://www.theguardian.com/uk-news/2021/aug/19/onlyfans-to-...
Ultimately the ban was undone in exchange for onlyfans limiting the type of content available on the platform. So effectively, payment processors dictate which type of sexual activities, performed by consenting adults, are OK to depict and sell. Why? Why do they have that power?
The government historically uses the the financial industry to police crimes and behavior that it does not want to or that it is not expedient to police directly. Clearly they like the outcomes of the payment networks' rules and enforcement decisions and see no need for things to change.