In case of modern LED lamps, the flickering ratio can be between 0% and 100%. That cannot be perceived often.

However, the health-related consequences can be fatigue, lack of concentration, reduced eyesight, headache and even epilepsy.

Certainty is brought here only by measurement of the flickering ratio.

Flicker analyzer ZadPad Lightmeter LM10
Video flicker measurement Light flicker meter LiFli