I've had the Delta Reserve card for three months and just tried the Resy thing for the first time at lunch today . . .Pomegranate Bistro in Redmond, WA (suburban Seattle). I ordered a chicken pesto flatbread for takeout. No credit posted to the card yet, but I do have a charge for "Resy Network" for $1.94, and then an offsetting credit for $1.94 for "Restaurant Transaction".
BTW, who is eating the cost of these Resy credits? Delta? Amex? Resy? The restaurant? Or do you suppose it's shared by two or more of these entities?