Dryer duct is old. Modern dryer vent installations and materials are much safer & efficient.
The duct for your dryer is made of flimsy or foil ducts. Although those are often the cheapest options, these types of vents accumulate dust and lint very easily and are much more flammable.
Your clothes are taking too long to dry. This can be caused by the vent being blocked or torn which can cause your drying machine to be inefficient and put your home at risk.
Your Dryer Vent & Duct has not been professionally cleaned in over a year.