The Bug:
When adding a fence and a the top adding pressure plate you can active the block by only going near to the block instead of activating while going on top.
Steps to reproduce the issue
Grab fence and pressure plate or craft (if not already did)
Place the fence
Then, place pressure plate on top of the fence
now the player move to near to the fence block
Expected result
the player would not activating the pressure plate by only going near to the fence block.
Actual result
the player would activating the pressure plate by only going near to the fence block.
This is how pressure plates have always worked in all editions of the game. See also that (MCPE-80276) was fixed to restore this behavior.