[Nasrudith]

Essentially they must allow the user the option of Apple as a payment mechanism to ensure their feature is unbroken. The no lower part is that they can only discount up to whatever Apple's cut would be if they use their own payment mechanism. Related to the first point to prevent "soft disables" like setting Apple pay price at something dramatically worse that few would pay. Charging $13 through Apple and $10 through theirs ensures they get their $10 no matter the customer choice. Or they could call the volume worth the cut and charge $10 for both methods.

Setting it worse opens up effectively a "soft disable" like Apple price at $1000 and their price at $1.

If they for some reason decided to charge $1 through Apple and $1000 through their own that poor decision is no skin off Apple's nose.