Your camera uses an infrared-cut filter placed in front of the lens.
During the day, this filter blocks infrared light to ensure natural colors. At night, it moves away to allow infrared illumination.
If the filter is stuck in night mode, the image may look pink or purple during the day.
If the image stays black at night even though the infrared LEDs are on, please reboot your camera electrically.
When the camera reconnects, if the issue persists, this also usually indicates that the filter is defective.
Updated