PistonArmCollision is visible while moving a block

If you push or pull a block with a piston, for a brief moment pistonarmcollision is visible. This is most noticeable in slabs and other blocks that are not a full block. In regular pistons, in the extended head, you can also see pistonarmcollision. I have a picture of this, but the upload thing seems to be broken so you can find it at https://imgur.com/XksgnEo