Found this as part of Westpac's offer via mobile app. Seems like it is part of the rewards program offered via WBC Black Card.
Example of offer - spend $50SGD in Changi Airport and get $15SGD back. Valid from July-September 2019.
https://www.loyaltygateway.com/rewards/phoenix/Mastercard_Tr…
Site description:
Welcome to Mastercard Traveler Rewards
Enjoy exclusive, automatic cashback offers from participating overseas merchants when you travel, shop and pay with your enrolled Mastercard* - online or instore.
Explore the wide range of international merchants and offers available where you can enjoy the benefits as an enrolled* Mastercard cardholder.
And it's ready to get. Just cilck the link!