I was reading this question: What is the counter-force to suction force?
OP says pressure ends up uniform everywhere after some time.
I don't see why unless there is a dissipation of energy. If there is sound, for example, in a closed reverberant room, the pressure waves will decay only through absorption of the walls, being imperfect reflectors.
But maybe I am taking air to be a perfect conductor of sound while it is not really, losing focus (high frequencies) over time.