I, too, have this situation with my 2019 Chevrolet Silverado. When my truck is turned off, the trailer lights on my horse trailer continue to flicker repeatedly every 10-15 seconds forever. I’ve resorted to unplugging the trailer to avoid any draw on my battery.
NEW: I read not to long ago on this forum site that GM had come up with a fix. Some type of new computer module? My Chevy dealership had never heard of it so I had to furnish them the #specs from the Forum article I had read. It’s as yet, not a formal recall. Anyone know any more news on this issue?