If you activate a piston with one rail in front of it (all) and a block in front of it an offset down another rail places the piston activated the bottom rail stays up on the block although no other rail is connected to it.
If you activate a piston with one rail in front of it (all) and a block in front of it an offset down another rail places the piston activated the bottom rail stays up on the block although no other rail is connected to it.
this has always been like that and should never be changed, used in lots of contraptions, while fixing it comes with 0 benefits