Its unclear exactly for sure which advertisers/businesses are being targeted with this but Google Adwords has been sending out notices to some customers that starting this summer (different dates for different people) you will no longer be able to pay your Adwords bill with a credit card rather can only pay via direct debit or invoicing and paying by ACH.
Some customers have theorized that Google has made this move to save on the ~3% credit card processing fee however Google has not confirmed this.
Many businesses that have high charge volumes of 7 to 8 figures annually using cash back cards or point cards stand to see a substantial number of points or cash back disappear. We know some companies rely on these rewards to help their bottom line.
We hope that this change does not ultimately extend to all customers!