I dont know is that a bug or not

What I expected to happen was...:
I just make a Trap for something funny but I saw a Trap Chest is give power to a piston (in the picture) and I dont know why it happen like this

What actually happened was...:
Piston was activating but is not have any redstone above them and another picture i just placing block. another piston is activating too
i dont know why can somebody tell me!!!!

Steps to Reproduce:
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