Why does the Xiaomi 4K Monitor A27Ui show colored stripes when photographed with a phone or camera?

This is a normal physical phenomenon for the Xiaomi 4K Monitor A27Ui known as moiré patterns. Almost all devices will show such stripes when capturing a computer screen due to differences in refresh rates.
For your reference, here is more information about moiré patterns on the monitor:
  1. A video is essentially made up of many sequential photos captured over time, with an average shutter speed of about 30 frames per second. Meanwhile, monitor screens have a refresh rate around 50 Hz to 60 Hz. When these two frequencies are not aligned, it causes visible flickering or scanning lines in the video;
  2. To reduce this effect, you can try adjusting the camera's shutter speed or frame rate to match the screen’s refresh rate.

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