After buying a usb wifi dongle I noticed this strange behavior:
If I plug it after the system is booted, the network preflet doesn’t show the network card. If I boot with the dongle inserted, the network card shows up in network preflet, but if I unplug the usb card, the network preflet still lists it.
Ok, there was a bit of misunderstanding, your comment sounded like it was for all network adapters in general, but it is only for the ones using the BSD compatibility layers. It works fine for native drivers like usb_rndis.