I also have the same issue with my 2021 Yukon Denali. Practically from the time I got it, if it sets for several days the battery would be low. Like there is a drain. A couple of months ago after driving it, I parked for a few minutes then couldn't start it. The battery was completely dead. After the battery was replaced, I no longer have the problem. It can set for a week and it seems to still be fully charged. I'm now wondering about the amp capacity of the battery that comes with the new vehicle, as compared to the replacement. Did I get a low capacity or defective battery to begin with. I also wonder if there was an update downloaded that maybe corrected the drain issue. I got very tired of the dealer telling me there was nothing wrong and that I should just drive it more.