Is it Fiserv? I notice Mastercard invested into PayPal and Fiserv just a couple months ago, and PayPal was already in business with Fiserv via Fastlane.
Also Bandcamp.com refused to accept the payment from my credit card and I contacted my bank and they told me that payments to Bandcamp are always blocked because of security reasons(that is their policy) and they had to manually approve my credit card for use on Bandcamp....which is totally fu*king crazy. Manually approving payment transactions in the 21st century is wrong. How the hell should I know which vendors are on my bank's blacklist?!
Tbh or at least that's my impression all comes down to the problem of fraud and crime. That's why we still have shitty payment providers and processors.