NHTSA Complaint #11452458 — 2021 TESLA MODEL Y

I've been having problems with phantom braking, primarily on highways. This problem has gotten much worse in the last month or two. The car will unexpectedly brake while either autosteer or adaptive cruise control are engaged while driving on the freeway, and typically (although not exclusively) when my speed is approx. 70-80 MPH (where speed limit is 75-80 MPH). This will happen approx. once every half hour, although it is sporadic and often happens in spurts. Until about 1 month ago this would happen only while autosteer was engaged. However, during the last month or so ago this has also been happening while adaptive cruise control is engaged (without autosteer engaged). It happens most often when I am in the left lane passing a semi-truck which is in the right lane, although it happens other times as well. Always without any warning. It has happened a total of probably 20-30 times in the last 2 months (approx. 5,000 miles). Sometimes it manifests as a gentle, almost tentative tap on the brakes, whereas other times it is a fairly jarring with sudden hard braking. It has not caused any accidents or incidents, but I am concerned about it happening when a car may be behind me. Because of that, I will often disengage cruise control or autosteer if other cars are close behind me. My car software is equipped with Full Self Driving, but the FSD (beta) has not been downloaded.