The deal is valid when paying via Apple Pay through the Grubhub app and website with promo code CELEBRATE20. The code is one-time use for personal Grubhub accounts and offers a maximum value of $10 on order subtotals before taxes, tips, and fees.
In addition to Grubhub, Apple’s email also promotes other ways to use Apple Pay to “ring in the new year,” including movie tickets on Fandango, hotel deals on HotelTonight, and car rentals through Turo. Finally, Apple notes that it’s the last chance to receive 6 percent back on Apple Store and apple.com purchases when paying with Apple Card through December 31.
https://www.macrumors.com/2019/12/27/apple-pay-new-years-grubhub/