Camera flickering while shooting slo-mo

If you're shooting video indoors, that is perfectly normal if you're shooting under LED or florescent lights.

Depending where you live in the world, electrical current runs at 50 or 60 cycles per second. When you shoot in slow motion you are picking up those on and off cycles. It's too fast for the human eye to pick that up but the camera does.

LED & florescent lights respond very quickly to the voltage drop, incandescent lights don't as much because the filament doesn't cool down quickly.

It’s normal because the camera sees and records the light dimming and then increasing. High end cameras have switches and variable controls to adjust the shutter speed of the camera. iPhones do not have that ability at their price point.

This happened to me it’s a very basic problem basically if you are filming under a light as in a light bulb it flicker and you can’t see that but when in slow mo the phone detects light and sees that it’s flickering

I already explained it. No there is no glitch, the flickering you see is because LED and florescent lights flicker as the voltage turns on and off. The iPhone's camera sensor is fast enough to capture the on and off cycles.

I've explained this to you twice, I've nothing more to say.