Won an international giveaway. Now being asked to pay $27 to customs?

The giveaway was for 1 sealed pokemon pack. So I won't be paying that 😂

What do I do? Did the seller mess something up where they enabled the incorrect shipping, and now they're trying to pass it on to me? To be clear, this was a note left on my door from USPS itself, and on USPS's website, so it's not a scam