I just checked the rules because I hadn't heard of that, and yes it is a new rule that was added January 8th. It basically says that you cannot violate your payment service's terms of service, so for PayPal you cannot charge a fee but for something else, like Square cash, you CAN charge a fee for it IF Square would allow you to do that in its terms of service.
The rule makes sense, but PayPal policy does not to me and frankly I question he legality of it in some states. I know that quite a few places charge a fee for credit cards now, this is no different.
But regardless, I learned something new too and that is one sweet book! GLWTS!!!