We're big fans of the iPhone 13 Pro and iPhone 13 Pro Max's 120Hz ProMotion display, but there seem to be some issues with this new feature.

As 9to5Mac discovered, the new iPhone's 120Hz ProMotion display is not working as expected with some third-party apps, causing the software to revert to 60Hz in animation. Fortunately, Apple is aware of this issue and a fix is expected soon, although the exact timing is unknown at this time.

The ProMotion display, which can jump between 10Hz and 120Hz on demand, is the star of this year's top-end iPhones; in a review of the iPhone 13 Pro, phone editor Jordan Palmer was quite pleased.

"Once you experience a 120Hz display," he wrote, "it's hard to go back to a 60Hz one." The same is true of the iPhone 13 Pro, which has a noticeably smoother screen than the 12 Pro." He continued, noting that the crisp animations and smooth performance make for a "very premium experience."

Therefore, it is very unfortunate that the display is not working properly with some third-party apps, but if it were consistently locked to 60 Hz, or 60 fps, this would not be a major issue.

However, as 9to5Mac points out, some apps inadvertently combine 120Hz scrolling and full-screen transitions with 60Hz animations; as this comment on the Apollo app shows, it is hard to miss:

initially that this third-party limitation was intentional, an examination of the iOS 15 code revealed that first-party Apple apps were excluded from the limit, but Apple has since clarified that this was not intentional. The company told The Verge that two things could cause this issue.

The first is that developers need to update their apps with a flag declaring support for 120Hz mode, which can be done by adding an additional entry to the app's Info.plist key. According to Apple, a document clarifying this will be released soon.

The second is an old-fashioned bug: there is a problem with some animations created using Apple's Core Animation technology, which will be fixed in a software update soon.

As frustrating as it may be, this issue should not deter you from purchasing an iPhone 13 Pro or Pro Max. In fact, we have been greatly impressed with all four models in the iPhone 13 series; three of the four models are on our "best phones you can buy" list, and our battery tests of the iPhone 13 show that the weaknesses of the previous generation have been markedly improved.