Household appliances that are exhausted through the Attic space must be connected to the proper roof vent. Bathroom fans, Clothes dryers and Kitchen hood exhaust fans are all vented using a type of Gooseneck Roof Vent. Goosenecks are installed much like an exhaust vent but do hold one key difference: an interior connection that allows exhaust pipes & hoses to be fastened directly to the vent. This provides for continuous air flow and eliminates any heat or moisture from escaping into the unconditioned Attic space.
Moisture, condensation, mold and wood rot can all result from breakdowns & errors in how vent hoses/pipes are exhausted. A very common error we find in Attic inspections is a bath fan vent pipe simply pointed at or leaning against a turtle exhaust vent (pictured below) instead of connected to a proper Gooseneck. Although it may look harmless the gap between the vent pipe and hole in this roof is a recipe for problems. Although some hot moist air will escape of out of the turtle vent, much will spill back into the Attic space. The plywood in this picture looks quite new which may indicate that it was deteriorated and replaced during the last roof replacement. Where most likely the roofer made an error and installed an exhaust vent where a Gooseneck Roof vent should have been used.
bath fan exhaust pipe pointed at incorrect turtle exhaust vent
The good news is that this is a simple fix: the shingles can be taken apart in this area, the vent pipe can be replaced with a new pre-insulated flexible exhaust hose, the hose connected to a new Gooseneck roof vent and the shingles put back together to continue to shed water.