Blocks moved by a slime clock flicker - becoming invisible while moving.
Moving slime block Z-Fighting with attached blocks
When a piston retracts, the piston will sometimes becomes transparent for a split second
Glitches of Redstone Machines
Blocks flicker when moved by slime blocks
redstone blocks don't render with 0 ticks pulses with sticky pistons
Block lag / Door delay / Pressure plate stuck