We have a May 2021 LR Y with Vision 8,000 miles so far. My wife has complained for a while about how bad the cruise control is (not even talking AP). She has had several incidents now where she was nearly rear ended. I was able to use it a few days ago at night and was shocked just how bad it truly is. In a 25 mile stretch of 2 lane highway (1L1R lane) I received probably 10 audible beeps and hard breaking events while oncoming cars are passing. Other times the car will hesitate dropping speed 5-10 mph. It appears the system is similar to the other autopilot systems, when there is a lead car it locks onto it and is somewhat stable. However, when you have open road in front at night it consistently freaked out.
I saved video clips of these events and took bug reports as they occurred. Really disappointed when Tesla cancelled my service appointment referencing auto steer as a beta feature, training neural nets, and to wait for future firmware updates.. I'm going to try again as this really isn't auto steer but the TACC.