That is the "Secondary CVT cooling air inlet" you'll find the rubber tube attached to the back side of the inlet box. It goes to the center of the Secondary Clutch location of
the CVT, or clutches housing.
But...you really need to seal it up to prevent dust from getting into the CVT housing.
Shine a flashlight through the Frogzskin cloth and look inside the fender well. You will see light where it's escaping the inlet box. Use a heavy aluminum tape to seal up where you see light.