Component used: Navigation
Version used: 2.8.0-beta03
Devices/Android versions reproduced on: emulator

Suppose the class for the route is NotHome.

@Serializable data class NotHome(
    val param: String? = null
)

Suppose the destination is set up like this.

composable<NotHome>(
    deepLinks = listOf(navDeepLink<NotHome>("example.com")),
) { bse -> 
    val notHome: NotHome = bse.toRoute()
    Text("param=" + notHome.param?.let { "'$it'" })
}

When the link is https://example.com?param=NULL, param is string 'NULL' as expected. But if the link is https://example.com?param=null, param is really null instead of string 'null'.