Steps to reproduce:

1. Open attached project (device-enum-test.zip)
2. Switch to iOS and make a build
3. Build the Xcode project and deploy to a new generation iPhone 15 device

Expected result: the first line on screen displays Device.generation value, which should be iPhone15 (or Plus, Pro, ProMax depending on the device).
Actual result: Device.generation returns Unknown

Note: this is also visible in the Editor through Player Settings/Editor/Unity Remote section, if you expand '{}Device{}' dropdown with the device connected, it will say something like '{}Unknown: iPhone{}' instead of the actual device model (screenshot below).

!unknown.png!

Reproduced with: 2022.3.11f1, 2023.3.0a14

Devices tested:
iPhone 15 Pro, iOS 17.0.2 - Reproduced
iPhone 15 Pro Max, iOS 17.1 - Reproduced
iPhone 14 Pro Max, iOS 16.0 - Not reproduced