2021 Honda Odyssey Cruise Control Problems

Once the cruise control is set, it consistently drops below the set speed and surges back up or over the set speed. Set on 62, it drops to 59 or 60, then surges back up to 62 or 63. This happens on perfectly flat roads with no traffic in front or beside the car. The dealership tried to tell me that the camera for the adaptive cruise might be seeing things in its peripheral vision area, but there is nothing there, the shoulder of the road is wide and free of obstacles. I've owned many other brands of vehicle, and never had this trouble with the cruise control on any of them. This is also a safety issue because sometimes it just randomly slows down or speeds up when there are cars behind you or beside you.