Need HVAC advice ...return not connected to return plenum

I am considering buying a condo and when I first looked at the property I noticed the HVAC system's blower was in a small closet. Upon closer observation I saw that the air return grill in the living room wall was connected to a duct that was never connected to the blower intake plenum. See photo below.

When I had the property inspected the home inspector also noticed the same situation. The Trane HVAC blower was installed 6 years ago.

Is this a faulty installation?

Thanks for your help