The piston, set to the «extended to true» state, destroys the block in front of it after activation.

If you put any block in front of the piston using the debug stick to set its state to «extended to true» and then activate it, the block that stood in front of the piston will be destroyed. Reproduce:

• While in creative mode, take a piston, any activator (I used a lever), any block, and then give yourself a debug stick using command /give @s minecraft:debug_stick or take it from the operator's tab.

• Put down the piston.

• Put an activator next to it.

• Place a block in front of the piston.

• Take the debug stick and use it to set the piston to the «extended to true» state.

• Activate the piston.

• Nothing will happen.

• Do it again.

• The piston will slide out and break the block that stood in front of it, after which it will slide back in.