Transfers from other GrabPay users
Bank account top-ups via PayNow VPA or linked UOB accounts
In fact, there’s very little reason why you’d want to use a Visa credit card to top-up your GrabPay wallet anyway.
Visa’s reclassification of GrabPay top-ups as MCC 6051 (quasi cash transactions) in July 2020 effectively killed off the prospect of earning rewards, because virtually every bank considers this an exclusion category.
For example, it would make no sense at all to use your DBS Altitude Visa to top-up your GrabPay wallet and then pay with GrabPay, since you could have earned your regular rewards by just paying with the DBS Altitude Visa directly.