Piston hitboxes

I linked a piston to a 10 Hertz clock.
1. I'm able to mine blocks through a piston at some states of its extension or retracting process.
2. When I walk into a piston from it's front side, I get teleported to its back.
3. When I stand on the piston arm, I glitch around.
Video: https://youtu.be/bntkGIJNz0Q