Update | Cheeky Google: The Pixel 4 throttles the display refresh rate based on brightness setting, and you wouldn't even know it
Update: Google has acknowledged this behavior and will be releasing software updates to allow for 90 Hz refresh rate in more brightness conditions. In a statement to The Verge, Google said,
We designed Smooth Display so that users could enjoy the benefits of 90Hz for improved UI interactions and content consumption, while also preserving battery when higher refresh rates are not critical by lowering back down to 60Hz. In some conditions or situations, however, we set the refresh rate to 60Hz. Some of these situations include: when the user turns on battery saver, certain content such as video (as it’s largely shot at 24 or 30fps), and even various brightness or ambient conditions. We constantly assess whether these parameters lead to the best overall user experience. We have previously planned updates that we’ll roll out in the coming weeks that include enabling 90hz in more brightness conditions.
The Google Pixel 4 is surely a great Android device but is not without its share of criticism. While the 90 Hz Smooth Display is a welcome feature, it is a power guzzler and the low battery capacity of the device actually defeats the purpose of having one.
Google said that the display's refresh rate is adjusted dynamically between 60 Hz and 90 Hz depending on "some content". However, it looks like the phone decides on the refresh rate not based on usage or content but on screen brightness. This was first discovered by Redditor u/OrganicNebula by monitoring ADB logs while working on a software project. XDA's Editor-in-Chief Mishaal Rahman later tested it using ADB and logcat and confirmed the same.
According to Mishaal, if the brightness is less than or equal to 75%, the display works at 60 Hz and if the brightness is above 75%, the display switches to 90 Hz. You can actually test this yourself by visiting Blur Busters' testufo.com website and check for change in refresh rate by adjusting the brightness slider.
Why Google chose to club refresh rate with brightness is still unknown. In fact, phones such as the OnePlus 7 Pro and the Asus ROG Phone 2 (buy it on Amazon) sport similar high-refresh rate displays and the setting is independent of brightness levels. In the same Reddit thread, XDA's Dylan Raga noticed that Google applies a different calibration curve when setting the brightness below 20% magnitude (~75% on the brightness slider) in order to boost shadows, which causes the refresh rate to fall back to 60 Hz.
So essentially, you get to see the actual high-refresh rate only when setting the brightness above a certain threshold. This is a letdown of sorts as it is not often that users crank up the brightness above 75%. For the moment though, this looks to be a feature and not a bug. Conversely, the refresh rate can still apparently stay at 90 Hz on low brightness provided that the ambient lighting is "super bright".
However, there are ways to force the display refresh rate to always run at 90 Hz by toggling the "Force 90 Hz refresh rate" option in the Developer settings. You can also use this custom Tasker task to create a "Force 90 Hz" shortcut in the quick settings area. Do note that this will have a considerable impact on the Pixel 4's already not-so-great battery life.
Are you a Pixel 4 early adopter and have noticed this odd behavior? Let us know in the comments below.