execute as @e[type=minecraft:zombified_piglin] at @s unless entity @e[type=chicken,distance=..0.4,nbt={Passengers:[{id:"minecraft:zombified_piglin"}]}] run tp @s ~ ~-50 ~

execute at @e[type=minecraft:zombified_piglin] run tp @e[type=chicken,distance=..0.4,nbt={Passengers:[{id:"minecraft:zombified_piglin"}]}] ~ ~-50 ~