Thanks - please keep me posted if you notice any more severe behavior, like some stories I've heard of the cruise speed suddenly changing from 120 km/h to 40 km/h. My ID.4 has "adaptive cruise control" (like TACC, as I understand it), but it normally acts by slowing the car with the motors, using the brakes only if there is truly imminent danger of collision. Very smooth in slow-and-go traffic.
ID.4 also has "lane assist" that will try to gently steer back into the lane if I drift. This happens sometimes it shouldn't, such as when two lanes merge and the road texture changes. A little disconcerting, but it doesn't feel like a potential danger.
I'm hoping the base Model Y's AP will be equivalent to the ID.4's ACC + lane assist.
Overall, I like the ID.4, but am driven to abandoning it because of its shorter range, slower charging speed, very sparse charging network, and VW's terrible mishandling of the current mass recall of the 2021 model (a severe danger of sudden power loss). Apparently it's just a software fix, but VW may take months to fix it.