Moisture damages wood. Just about everyone knows moisture damages wood. Moisture rusts and deteriorates metal. Joist hangers are made out of metal. Exhausting clothes dryers under wood decks with metal joist hangers is just a bad idea.
Relocating the clothes dryer exhaust is much easier than relocating the wood deck. If neither is relocated damage to the deck structure at a critical point will continue to occur.
Additional problems depicted in the photograph include deck ledger board bolts that are too small. Installation of additional deck joist hanger bolts is necessary in order to avoid movement (failure) of the roof deck structure.
Looking at the photo it appears the underside of the deck structure is already mold and or moisture damaged. Corrective actions are necessary to cure the existing hazards and to avoid further damages.
Clothes that come out of the clothes washer weigh more than clothes that come out of the clothes dryer. Every 8 or so pounds of weight difference represents one full gallon of water vapor that will accumulate under the deck structure causing damages to the wood structure and to the metal joist hangers that support the weight of the deck structure.