Yes, phantom braking can be a thing with any Tesla model with adaptive cruise control that is a part of basic autopilot, enhanced AP and FSD. I have a 2017 Model X and 2018 Model 3, and they behave mostly the same. My personal experience is that I no longer experience the horrible, soul-jarring phantom braking that once occurred. They tended to be with shadows in the road or with overhead bridges, but were always extremely sudden and severe slow downs. Now, the only thing I experience are more like phantom hesitations. Annoying but not alarming. And very seldom.
A 2019 MX has radar, but the latest updates going out are reportedly disabling it on cars that have it. Both my cars have radar that was disabled about a year ago when I joined FSD Beta.
I am a big fan of autopilot. It has been a game changer for me for long trips. It is extremely good. But one still needs to pay attention, and there are times when you need to intervene.