Even though I renewed my pass a couple of weeks ago, I just got a renewal letter in the mail today. It says, among other things "Plus, you'll receive a coupon good for 20% off your next purchase of $50 or more of select merchandise at the
Disneyland Resort." I have a Premium AP and already get 20% off merchandise, so no extra benefit there.
No other mention of 20% off anywhere. Just $60 off the Premium Passport.