Why do the author need to add remember for a variable from viewModel?

Question

The Code A is from the official sample.

In my mind, I needn't to wrap a variable from viewModel because it has more long life cycle.

But why do the author need to add remember for a variable from viewModel ?

Code A

@Composable
fun DetailsScreen(
    onErrorLoading: () -> Unit,
    modifier: Modifier = Modifier,
    viewModel: DetailsViewModel = viewModel()
) {   
     val cityDetails = remember(viewModel) { viewModel.cityDetails }
     ...
}


@HiltViewModel
class DetailsViewModel @Inject constructor(
    private val destinationsRepository: DestinationsRepository,
    savedStateHandle: SavedStateHandle
) : ViewModel() {
    ...
    val cityDetails: Result<ExploreModel>
      ...
   }
}