Google has added 90Hz OLED displays to both its Pixel 4 and Pixel 4 XL phones to allow a smoother Android experience. Unfortunately, the company has also linked this refresh rate to the display brightness level of Pixel 4. Reddit users have found that Pixel 4 will drop to 60Hz refresh rate after display brightness drops below 75 percent. The Verge confirmed this on a Pixel 4 review and it means that you only get the full 90Hz display frequency when the brightness level is high.
This is good for outdoor use, but the majority of indoor use will mean that the brightness level is likely to be 75 percent or lower. It's not clear why Google chose the 75 percent mark, but droidlife found that you could target the developer settings and force the 90Hz setting to always be activated, regardless of the brightness levels. This will probably affect the life of the battery, which is something you will want to think about before forcing the 90Hz display to always turn on.
Other 90Hz OLED Android phones, such as the OnePlus 7T, keep the display running at its maximum 90Hz time, but Google said it would automatically switch the pixel 4 display refresh rate "for some content." information on how and why it limits the refresh rate of the Pixel 4 display and we will "update you accordingly.