Detect player motion [1.21.8]

Hi !
So I want to detect if a player isn't moving.
I tried with execute if entity @p[nbt={Motion:[0d,0d,0d]}] run x, but it'll pass the test as long as the player isn't moving on every axis, and I want the test to not care about y motion.
I considered just grabbing the x and z Motion values from the player's nbt, putting them in a scoreboard and comparing them afterwards, but I was wondering if there was a quicker way to do so, perhaps with predicates or with something I missed about my command.
Thanks for the help !