Just in case anyone is on the line about whether to buy - I would wait if I could do it over again.
Ordered a 2021 GMC Yukon Denali. Traded my 2016 Yukon Denali and put $5K down and a friend gave me an employee discount code to save over $4.5K off sticker. Drove 2021 Denali off lot with only 2 miles on it. Drove it home to discover rear headrest would not stay upright. Drove back to dealer the following day, they looked at it and scheduled appointment 2 days later. Drove it the next day and "Service Driver Assist System" warning came on. Dropped it at dealer the next morning with 62 miles on it and they kept it for 8 days to replace the headrest and replace driver assist front radar module. Picked up from dealer on afternoon of 8th day and it had 124 miles on it due to the "testing" they did. Stopped at a store on the way home and noticed the park assist lights came and beeping on when there was nothing around me while parking. Later that night, drove to empty parking lot and recorded the vehicle malfunctioning over and over with park assist lights/alarms while nothing around the vehicle and screen blinking/glitching. I will post a video if I can.
Took it back to the dealer today and I can only imagine how long they will have it this time. At this point I'd just rather it be more than 30 days so I can file a lemon claim.