While playing on my survival server with the new snapshot for a day or so I noticed that neither pistons nor chests were animating when used. But there was something special with pistons; when going through my piston doors or activating any pistons, duplicate pistons appear floating outside my house in the positive Z direction. However, the duplicate pistons distance from the original was further in the Z direction if its original was higher in the Y coordinate. These duplicates were animated, unlike the originals - but they are not real, the server kicks you for flying when standing on them, and updating them causes them to disappear.
Multiple users on my server have all seen the same issue regardless of their personal setup. I think this issue expands beyond just pistons as well. We also experienced a random chiseled quartz block above the ground in a member's home, that when stood on, kicks you for flying and the block disappears.