Blue smears appears while scrolling in dark mode with extremely low brightness. This is because you are using am Amoled screen, this happens to every Amoled display. Most OLED panels use a technique called Pulse Width Modulation (PWM) for dimming its brightness. This is different from DC dimming, which has been used by LCD panels to control its brightness levels.
Yes. It can be reduced by DC dimming, but DC dimming has a big drawback. At low levels of brightness, the colors often come out skewed on OLED panels. In OLED panels, a change in voltage could change the emitted colors. So, at lower levels of voltage, the perceived quality of the smartphone display could go down significantly. So don't use phone with extremely low brightness, try to keep comfortable brightness and keep a decent distance between you and your smartphone screen.
