Is the ventilation system connected incorrectly?

Not here, I would never have expected that in my life either. Roughly 30 m³/h through an open door (0.5 m by 1.8 m) results in a speed of less than 0.01 m/s. Typically, air also passes under the door through a somewhat larger gap, and the residents can still open the door effortlessly. Your doors apparently are very easy to move!

well, 30 m³/h is really set very low. my system blows something around 150 m³/h through. and it is not the flow velocity but the pressure difference between the supply air side and the exhaust air side. our bathroom door definitely moves in the half-open state. the door being "almost closed" does not work like that, as it opens about halfway. (negative pressure in the bathroom due to exhaust air).

well, 30m³/h is really set very low. my system blows something like 150m³/h through.

But not through one connection/overflow, rather through the entire system. 30m³ is probably quite accurate if you assume, for example, 5 supply/exhaust connections each with the same volume flow.