Missing ceiling ventilation outlet in the hallway dramatic?

You have rooms with supply air where the air flows in, but the air must also flow out of the room again.
For this, either the bottom of the door is shortened or the frame is milled out so that the air can "overflow" into the hallway.
Then you have rooms with exhaust air where the air is drawn out, and the air flows there from the overflow area, the hallway.
This is how the air exchange in the house is created.

Then maybe it even makes sense that there is none in the hallway. As far as I know, that was planned as supply air. We have exhaust air in the kitchen, the bathroom, and the toilet.

Supply air in the hallway? Huh? What's that for?