_DeviceModel in UnityDeviceModel() in DeviceSettings.mm is returning the wrong value for an iPhoneX, so UnityEngine.iOS.Device.generation is returning the incorrect enum for an iPhoneX. It returns iPhone8Plus.

_DeviceModel is returning iPhone10,6 for my iPhoneX, but the test in UnityDeviceGeneration() in that same file, DeviceSettings.mm assumes 10,6 is iPhone8Plus.

Change the code at line 96 of that file in an iOS build to have an NSLog at the end, to say :

extern "C" const char* UnityDeviceModel()
{
static const char* _DeviceModel = NULL;

if (_DeviceModel == NULL)
{
size_t size;
::sysctlbyname("hw.machine", NULL, &size, NULL, 0);

char* model = (char*)::malloc(size + 1);
::sysctlbyname("hw.machine", model, &size, NULL, 0);
model[size] = 0;

_DeviceModel = AllocCString([NSString stringWithUTF8String: model]);
NSLog(@"device model: %s", _DeviceModel);
::free(model);
}

this returns iPhone10,6, which is tested in DeviceSettings.mm :

else if (!strncmp(model, "iPhone10,2", 10) || !strncmp(model, "iPhone10,6", 10))
_DeviceGeneration = deviceiPhone8Plus;

which is incorrect.