That is the vent.
Air comes in for A/C and Heat through the cowl...into the ducts.
It goes out through those holes.
Wagons they are in the tailgate.
Xt's they are in the door sill.
but all subarus have them.
vent hole so the cabin isn't a sealed box that can't accept outside air.
I may have to expand on this concept, as I have plans on replacing the sliding rear window in my Brats' cab with a center piece of glass, and panels directly behind the head for speakers to solve the problem of where to put (more) speakers. One narrow pane of glass in the center would not be able to be opened without obstructing the sound from the speakers on one side or the other, but I may be able to figure something out, as I think a vent there, high, between the seats would allow more air through when I have the T-Tops popped. I can also still use the holes here posted about to pass a couple of wires through for LED lighting effects for the Louver covers.