I've not had any pinch from CZ pistols but I did with a couple others like the Hellcat and a couple aftermarket Glock triggers.
For me the pinch came from just a small part of my finger was being squeezed (pinched) under the tip of trigger and the frame trigger guard. Took awhile to figure that out I assumed the dingus was the culprit but it was not.
The inside fleshly part of my trigger finger near the tip on the side nearest my middle finger was the area pinched, that fleshly part of finger was just the right size and shape to get squeezed under the trigger while firing, can't reproduce during dry fire only while live firing.
I believe because that part of the finger is so unique enough for each person and that's why the "pinch" is so random person to person.
An easy way to know if this is why you get pinched is to choke up really high on the trigger for a couple magazines, be sure you place your finger up as high as possible on the trigger so no chance your finger can get rolled under trigger between frame.
I wish I could just look at a trigger shoe and tell whether or not it will pinch me but unfortunately it doesn't matter the shape or length of the trigger shoe it is just weird random. Luckily I rarely have that issue but I certainly feel for the gun owners that do.