A spot on an iPhone screen is almost always a damaged matrix, not dirt or a software glitch. You can't remove it by wiping, restarting, or updating iOS: the color is formed by the pixel itself, and if it's dead, there's no image at that location. The only repair is to replace the display assembly.
Four different defects called a "spot"
- Black dots. Dead pixels. They don't grow or disappear, but there may be more of them over time.
- Ink bleed. A dark spot with a blurred edge that grows every day. This is a damaged matrix layer — the most urgent case: within a few weeks it can cover half the screen.
- Light or rainbow spot. The result of pressure: the phone was in a back pocket, in a bag under weight, or something was leaning on it. The matrix is dented.
- Stripes across the width. A flex cable is coming loose or the controller is damaged. Sometimes they appear after a drop without any crack on the glass.
Why this happens
The most common cause is a blow or pressure after which the glass remained intact but the matrix underneath did not. The second most common is moisture: drops under the glass first create a light spot with a rainbow edge, then a dark one. The third is a manufacturing defect, which usually appears in the first few months. Overheating is a separate issue: a phone left in the sun or in a hot car in summer gets spots around the edges of the screen.
What not to do
Don't press on the spot, heat the screen with a hair dryer, or "fix pixels" with colorful videos — these are all forum tips that don't work for OLED. Pressure and heat expand the affected area rather than shrink it. If the phone has been in water, something else is more important — what to do immediately after liquid gets in: every hour counts.
What the service does
First, diagnosis: the technician distinguishes a matrix defect from screen burn-in and checks if the problem is in the flex cable — then the display won't need to be replaced. If the matrix is damaged, a new display assembly is installed. When the glass is cracked but the image is intact, there's a cheaper option — replacing just the glass; we wrote about when this is possible in the article cracked iPhone screen glass.