Try one of these: https://a.co/d/08I5FYeD

Cats really only like to scratch on tall and sturdy things like trees or heavy couches

If their post isn’t tall enough, they can’t get a good stretch out of it

If the post tips over easily, they just won’t want to use it (you can also use a heavy weight to keep the base steady, but I find that solution rather cumbersome )