In the new snapshot, when a piston's (normal or sticky) state is updated from retracted to extended, or extended to retracted, the piston will blink instead of playing the intended 'moving block' animation.

I can confirm that in 1.11.2, the 'moving block' animation is used, so this must be unintended behaviour.

This applies to the piston and any and all blocks moved as a consequence of the piston (including those attached to slime blocks).

The attached screenshots demonstrate the before, during and after of each extend/retract.

HOW TO REPRODUCE
1. Create new superflat world.
2. Place down a piston, facing any direction that is not above the piston push limit.
3. Power piston with redstone torch, redstone block, etc.
ALSO TRY:
4. Place block in front of unpowered piston, and power the piston.
5. Place slime block in front of unpowered piston, also placing blocks on sides of the slime block, and power the piston.