Why the video screen twinkles and black lines appear when recording inside or under fluorescent lamp?

This is a normal phenomenon related to flicker of light source that occurs when the light source taking the form of a flashing

frequency of the fluorescent lamp to the camera.

Flicker phenomenon can mainly be generated at a shutter speed of 1/120 or more and it occurs in the characteristics of the CMOS sensor. This is
normal operation which can happen on all camera with CMOS sensor and it’s caused by CMOS sensor’s original specification.