MacBook Pro 2019 13" A1989. The screen turns white.

When I turn on the MacBook, everything works fine for the first couple of minutes, but then a whitish stripe about 3 centimeters wide appears across the entire screen. The screen starts to fade, as if covered in fog, to the point where the image becomes barely visible. This issue is especially noticeable during CPU-intensive tasks, such as watching videos or browsing the internet. When an external monitor is connected, the built-in display turns white instantly, but the image on the external monitor remains clear.

The CPU temperature at startup is around 40-45 degrees Celsius. Under load, it gradually increases and can reach 100 degrees after half an hour to an hour of intensive work. However, the screen starts whitening before the temperature begins to rise. The fan has been cleaned and is free of dust.

What could be the problem? Does the thermal paste need to be replaced, or should the built-in display be replaced?

Update: The temperature occasionally spikes to 90+ degrees and then quickly drops back to 70+.

Dear Dan, @danj, Thank you for your message.

Here is a screenshot of the app in operation. Everything fits on one screen because the image was displayed on an external monitor. On the built-in display, it really doesn’t fit without scrolling. At the time of this screenshot, the MacBook had been running for 4 hours with the lid closed, using an external monitor and an external Bluetooth keyboard.

60 degrees doesn’t seem too high (although on my 2022 MacBook, the temperature never exceeds 45). As soon as the lid was opened, the built-in screen was clear for the first second but started turning white right before my eyes. Here is a series of photos taken a few seconds apart.