There is definitely a lot of links in this chain. Maybe leafo [1] can chime-in and say exactly what happened. But I suspect that someone downstream of Visa/Mastercard anticipated that the payment card processors would not permit the transactions and relayed that back up to the merchants, and they shut it off preemptively.

But it's hard to say. Mastercard is now saying that they never said or did anything. So where did the outrage come from? Someone must have done something.

https://news.ycombinator.com/user?id=leafo