It appears that app developers will need to make some adjustments to take full advantage of the new 120Hz display on the iPhone 13 Pro and Pro Max.
The clarification came after some developers reported that scrolling in an app used 120Hz, but animations were capped at 60Hz. By adding the plist entry, applications can start to take advantage of the higher refresh rate.
Apple also noted that the iPad Pro doesn’t require this special setup. While it is not entirely clear why, Engadget suggests that it may be a limitation to help preserve iPhone battery life – the iPad would not need a similar limit as the larger battery would experience less shock from 120Hz.
In addition, Apple also confirmed the arrival of a solution for the animations of ‘Core Animation’ of some applications. In short, the bug limited the speed of these apps, but a future iOS 15 update should fix the problem.
In general, if you are one of the lucky ones who have a new iPhone 13 Pro and you notice that some applications are not as smooth as others, it could be because the developers have not yet updated the applications. As with all major iPhone screen changes, it can take a while for developers to add support.
Those interested can view the full Apple Developer Article. here.