This glitch is caused because the pillar no longer moves in increments that align it with the floor. This means that when the pillar is one block above the floor, the game thinks "Oh, there's still room, so let's move a couple more blocks!" which causes it to cut into the floor. I know not whether this unalignment is so that people can easily slip under the pillars to hide from the lightning, or something completely different. All I know is that it's weird. At least we have proof the red pillar has the power to break the floor!
![](https://i.ytimg.com/vi/IymjvFNjDuM/maxresdefault.jpg)