The widest part of the paintbrush is called shoulder. That is just where most artists hold their paintbrush to allow it to bounce and be ready to capture what’s seen and perceived. That is when movement of the wrist is at best potential and free from restriction. Are you really moving from the wrist? Try this:
Lie down on the mat in semi-supine with a bit of support under your head. Your hands are resting on your torso, wide and open.
Very slowly move your hands towards the ceiling without lifting your elbows. Observe your breathing without changing it.
Rotate your whole forearm back and forth sensing the weight of your bones.
Take that idea into standing, pick up your paintbrush and express the movement of your body with some paint.
What are you noticing?