https://wccftech.com/third-party-apps-on-iphone-13-pro-max-not-working-with-120hz-promotion/

One of the most significant changes Apple introduced to the iPhone 13 Pro and iPhone 13 Pro Max was a 120Hz ProMotion display, an upgrade not available on last year’s ‘Pro’ models. Unfortunately, some third-party apps cannot take advantage of this feature.

Developer of the Apollo Reddit client Christian Selig found out the hard way when he received his iPhone 13 Pro and discovered that third-party app animations were limited to 60Hz after receiving complaints from customers. Selig believes this limitation was put in place to conserve battery life because none of the iPad Pro models with 120Hz ProMotion displays exhibit this kind of behavior, with all apps running buttery-smooth.