https://wccftech.com/ios-14-5-and-macos-11-3-beta-code-references-a14x-chip-for-ipad-pro-and-two-unreleased-imacs/

A new iPad Pro and iMac models have been running wild in the rumor mill for a while now. While details on the release are scarce at this point, new references to the devices have been discovered in the latest iOS 14.5 and macOS Big Sur 11.3 beta code. If you are a developer, you can download the latest beta builds from the Apple Developer Center right now. For the iPad Pro, iOS 14.5 beta references an upgraded "A14X" chip while the macOS Big Sur 11.3 beta code references two unreleased iMacs.

According to findings from 9to5mac, the iOS 14.5 beta states a GPU from the chip which is referred to as "13G". While this is not the name of the chips adopted by iOS devices, previous naming schemes discovered in iOS suggested that the 13G reference corresponds to the A14X chip. The A14X chipset is a variant of the A14 Bionic processor that Apple uses in its iOS devices,