The previous version of the Web Monetization spec defined a paymentPointer attribute for monetization events. At the time, Web Monetization only supported payment pointers.

With v3, Web Monetization also supports Open Payments wallet addresses. For those not using Interledger's SPSP, the attribute name of paymentPointer could be confusing.

I think we've agreed that all payment pointers are a type of wallet address, but not all wallet addresses are payment pointers. I suggest changing the attribute from paymentPointer to walletAddress to minimize confusion.