A common reason is steam from hot showers. When moisture settles on the walls and later dries, it can leave behind yellowish marks or streaks, especially if this happens repeatedly in a damp bathroom.
Other possible causes include smoke residue, airborne particles, or buildup from soaps, sprays, and cleaning products. When these mix with humidity, they can create drips or stains that become more visible over time. In some cases, the streaks may also be an early sign of mold or mildew beginning to grow.
The best way to deal with the problem is to find the cause and address it. Better ventilation, regular cleaning, using an exhaust fan, and wiping down surfaces after showers can help prevent it. If mold is suspected, it should be handled quickly so the issue does not spread.
