The piston (sticky or not) didn't retract when it's unpowerd.
You need to have a piston facing down with a line of blocks on top.
Put a line of redstone dust on top of those blocks.
Power the redstone line.
It dont work the same everywhere (it depends of the chunck), and in every direction.
see https://youtu.be/CNGMDSzfhdA for exemple
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This happens due to the Redstone update order, its locational which means it acts differently based on where it is in the world. MC-11193

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I am unable to reproduce this issue in 21w20a.