Neither of my Gen3 Prii produce(d) an ABS chatter anything like my late-1990s ABS car did. These newer cars apply ABS far smoother. And yes, it is definitely being applied. I would not expect the Gen4 to regress.
Back in the 90s I had a 1988 Ford Granada Auto, which was my first car with ABS and the first Auto I had driven for a few years. I managed to make the ABS skid by accidentally pressing the brake pedal with my left foot thinking it was the clutch.
I thought perhaps my previous post may have sounded like "useless knowledge". I forgot to finish it. Because there is some wheel slip, you can expect at times to have a tire squeal/screach and you can expect at times to leave rubber on the road. Both depending on the type and age of the pavement and contaminants thereon. Finally, when the car gets close to the "success point" of stopping, I suspect antilock turns off. The pulse return rate will drop too low to be useful, and the last few feet might be a skid. This pulse rate is the output of the wheel lock sensors which you can almost always find in the wheel hub area along with the "toothed wheel" they run with. These sensors and their cabling are also the devices that were damaged when some tire monkey works on your car and you get an "ABS fail" indication afterwards. I didn't follow instructions to remove the sensor (it was stuck) when doing suspension work and I managed to rip the cable out of the sensor. A $185 lesson learned. In case you were wondering how I learned -my- lesson.