NT35510 4 inch display 800x480, part is dark

[Jorgen]

Dear all,
I am setting up a 4 inch 800x480 TFT display with the NT35510. The LCD component for ESP32s3 and IDF 5.3.1 includes an example for such a display. Hence it is easy to get started. I have removed all code related to LVGL and touch. I use a ESP32-S3 WROOM-1U module.

I have struggled to get something on the screen, but I have succeeded. I have the x-axis along the long side and the Y-axis along the short side. The origin is at the upper left corner. The connector to the left of the display area.

The 25% to the right (x-values from about 600 to 799) of the display flickers, and when the display memory is filled by a single color, this 25% has the color but is darker than the rest. I have used the draw bitmap function. I fill the display memory 80 horizontal lines (x-values 0 to 799) at a time.

What is causing this?

Has the display failed?

Regards,
Jorgen