The owners of that smash burger jernt where I'd had the bad burger, reached out to me and apologized and had figured out the problem - the chef used some new kind of cleaner to clean the grill just before my order - and apparently he didn't get it all off the grill. They offered to refund me but I told them DoorDash already had and they're now very cognizant of the problem and hoped I'll give them another try, which I will.
I hadn't had the Kung Pao before - I was surprised at the spice level, frankly.