Don't have something wrong with ur phone samsung won't do nothing about it an horrible customer service and management supervisors an president s off aint no better. I'll never deal with them again or bug there product
It's not a bug, defect, or meant to annoy you. It is a sensor under the screen, and detects when your ear/face is close to the phone screen, as it is when you make a call. If it detects your face, it turns the screen off in order to avoid accidental touches.
It's a much better solution rather than having a big notch at the top of the phone to house the sensor.