https://www.amazon.com/b/ref=as_li_...5ad630e432215ac14984937e195c8d&language=en_US
Bottom line, they're changing from a 20% discount to a $10 credit. The credit is good for 60 days, so use it or lose it.
Not clear whether Sony games will be among the ones selected for the discount. PS4 games have been ineligible for Prime discounts in the past few months. You haven't even been able to pre-order many PS4 games on disc, even at $60 (e.g., Spider-Man, last I checked).
Apparently Canada doesn't get the $10 discount.
It also includes no more ad-free Twitch viewing, for those who care about that.