I was playing with my friend, he was on top of a stair, and under that stair was a sticky piston. When my friend deactivated the lever, the piston lowered the stair my friend was on, it caused my game to stop and I had to close it. This happened twice!

That green is the piston side (textured). It was pulling the stair down, but it felt like a delay.

This is the piston side when pushing up the stair.

I also noticed that when the piston pushes a stair that the player is up on top, the stair instead of pushing the player up, it goes up and the player remains on the same block. Over the piston! He stays inside the stair.