Hung and replaced 14” duct that was leaking air onto the 7” supplying the bathroom made sure the bathroom duct had no rips or tears and was fully insulated Re caulked supply grill for the bathroom and caulked gap at wall above master bathroom toilet to ensure no more humid air from the attic or soffit vents would enter the room Advised customer if issue persists I would recommend a new 7”boot and duct replacement