2019 Toyota Highlander Collision Avoidance Problems

I was using the adaptive cruise control on I-68 in Western Maryland. I was in the fast lane (on the far left of three uphill lanes). A dump truck was in the center lane going well below the speed limit. The road curved to the left at the point where I got up to the dump truck. There was no one in front of me in my outside lane. My car sensed the presence and speed of the dump truck and slowed me abruptly. There was considerable risk to me and to the driver of a white pick-up truck that was behind me, and who was also driving at passing speed. We were both going approximately 75 mph when my car slowed--a slowing that does not display brake lights. The cruise control has not been inspected. It is the default setting on ignition. I routinely disable it, opting for regular cruise, each time I use it, but the potential is always there for me and for other owners. If there was any sort of warning (I don't remember) it would have been inadequate to prevent an accident. The alertness of the pick-up truck driver saved us both a collision.

DRIVING ON A TWO LANE ROAD FOLLOWING A CAR IN FRONT OF ME. CRUISE IS ON AND THE CAR IN FRONT OF ME IS NOT AFFECTING MY SPEED. THE CAR IN FRONT OF ME TURNS LEFT INTO THEIR DRIVEWAY AND IS COMPLETELY OFF THE ROADWAY. MY CAR BRAKES VERY HARD LIKE THERE IS SOMETHING IN FRONT OF ME. THEIR WAS NO ON COMING TRAFIIC. I'VE HAVE HAD THIS HAPPEN AGAIN BUT THE OTHER CAR WAS TURNING RIGHT. THE CAR WAS COMPLETELY OFF THE ROADWAY AND AGAIN MY CAR STARTS BRAKING VERY HARD. I WAS ALMOST REAR ENDED BY THE CAR BEHIND ME.