Good morning, sir,
I'm here to report a bug with the pistons:
By testing several times (to check if the bug is valid) I made a box of 3x3x3 blocks (type: that doesn't emit light) in the center place a block that emits light (campfire, glostston, etc ...), on one of the sides of the cube place (in the center) a piston (sticky or not), put the night (so that the environment is dark) and the piston transmits the light while the block is not transparent.
I guess it's a bug.

Have a nice day
2/4