If you’re reading the brake lights on the car directly in front of you as an indicator to slow down, you have already lost the plot.
A competent driver is actively driving a minimum of half a mile ahead of themselves with more than adequate distance between the vehicle directly in front of them to allow a response to changing road conditions.
The car doesn’t suddenly decelerate unless the driver completely pulls their foot from the pedal. This sounds like a skill issue on both sides.
I haven’t driven the id.4, but our car has a visual indicator that shows the percentage of regenerative braking efficiency achieved when you at coming to a stop. Hitting 100% is significantly easier in my experience with my test sample of 1 vehicle using the single pedal option, like everything though, I’m sure it’s not the same across the board.