I have a 2021 chevy 2500hd gasser and have the same issue. Had it to the dealer twice now. They replaced the switch in the tailgate which they said was bad. Lasted 5 days and is now doing it again. Worst of all I didnt always notice when it happened and always pull a trailer. The top of my tailgate is all bent in from hitting the tounge jack of the trailer. They said they will replace the tailgate when they figure it out, but this has been a long drawn out process. We cant be the only ones with this problem.