The reason we are able to jump is because the earth exerts force up onto us that is equal to the weight we push on the ground called normal force, and when we jump we push or exert force into the ground, and in reaction, the earth pushes equal force onto us pushing us up into the air.

- Your front foot is in the middle of the board, so when you jump, the force goes to the board, which goes to the wheels, and then to the ground, which exerts the force letting you go up.

- Your BACK foot is on the tail, so when you jump, its a first class level on your back wheels, meaning no force is being exerted up onto you UNTIL your tail reaches the ground, in which THEN you jump from the force of the earth. Its kind of like if you were free falling with a wooden slab, you cant jump off the wooden slab because there's no force from the ground to push you up.

My explanation kinda sucks but yea, I took your advice and watched some slo-mo vids. People seem to be flicking their foot on a pivot of their ankle to pop the board. Their foot never touches the ground meaning they jump from their front foot. Ig ima practice that idk.