DxOMark has published a long article on the causes of screen flickering on mobile phones and whether they can adversely affect vision. The source claims OLED screens are more likely to cause eye fatigue than LCDs.
The article points out that flickering occurs due to constantly turning the screen on and off. The pupil expands and contracts in response to changes in brightness. This involuntary physiological response explains why our eyes get tired after watching the screen for a long time. They are constantly working actively.
The light source power mode of LCDs and OLEDs dictates that these two technologies will have a flickering effect, however, the flickering effect of OLED screens is usually more pronounced than that of LCDs. The PWM (Pulse Width Modulation) frequency range of OLED screens is 50 to 500 Hz, and the PWM frequency of the LCD is over 1000 Hz. The human eye is sensitive to flicker at 250Hz, so OLED screens are more likely to cause eye fatigue than LCDs.
DxOMark also lists refresh rates and PWM frequencies for different mobile phone models. Among them, the mobile phone Samsung Galaxy S20 Ultra 5G, which is equipped with an OLED panel with a refresh rate of 60 Hz, has a PWM frequency of only 241 Hz. It easily causes eye fatigue. The same goes for the Samsung Galaxy S20 Ultra 5G. The PWM frequency of the Xiaomi Mi 10T Pro smartphone with a 144Hz refresh rate LCD panel reaches 2360Hz, which is much higher than the flicker sensitivity of the human eye.