While using the Galaxy A30, a small blinking hole appears at the top of the screen and light is visible. Why is this?

The bezel on the Galaxy A30 device was minimized because of the Infinity-U Display. Due to the minimized bezel, the Galaxy A30 has the proximity sensor underneath the display. When the proximity sensor is operated with a bright display while the screen is on, the light from the proximity sensor may be blinking and you can see a small hole flickering on the screen.  This is a normal operation and is not a device defect.