need help fixing a bug

im making it so horses with leather horse armor go up in powdered snow, unless there are 2 or more blocks of powdered snow ontop of eachother 
if this doesnt make sense i added a video to this post, in the 2 block tall powdered snow the horse isnt supposed to go up
i used this command: execute as @s at @s if block ~ ~ ~ powder_snow unless block ~ ~1 ~ powder_snow run tp @s ~ ~0.42 ~