Not sure if this is new but
Google Express had $20 credit for $50 spent on qualifying AMEX cards
Enrollment limited. Offer valid online only at express.google.com or via the Google Express mobile app. To see if delivery is available to your market, please visit google.com/express. Offer is non-transferable. Must add offer to Card and use same Card to redeem. Limit 1 statement credit(s) per American Express® online account. Statement credit will appear on your billing statement within 90 days after 12/28/2017, provided that American Express receives information from the merchant about your qualifying purchase.