You most likely have a white coating on the roof. Those coatings notoriously cause the streaks as moisture collects and then streaks down. A quality Ceramacoat won't do that. You might be able to stop the streaking if you paint over the old coating with a new seal coat.
"If it can't be reduced, reused, repaired, rebuilt, refurbished, refinished, resold, recycled or composted
then it should be restricted, redesigned or removed from production."