SwiftUI updates selection state twice when using List and TabView

I'm updating my watch app to support the latest features and UI on watchOS 10.

I want to implement NavigationSplitView, where the user will select a route from a List and view it in a TabView, where you can scroll between routes with the Digital Crown.

That's how I implemented it, following the tutorial on the Apple Developer website:

@State var selected: FavoriteRoute? // conforms to identifiable

var body: some View {
  NavigationSplitView {
    List(selection: $selected) {
      ForEach(favorites.routes) { route in
        FavoriteListItemView(route: route)
          .tag(route)
      }
    }
    .listStyle(.carousel)
    .navigationTitle("Better Rail")
  } detail: {
    TabView(selection: $selected) {
      ForEach(favorites.routes) { route in
        FavoriteRouteView(route: route)
          .tag(Optional(route))
      }
    }
    .tabViewStyle(.verticalPage)
    .toolbar {
      ToolbarItem(placement: .topBarTrailing) {
        NavigationLink(destination: SearchView(), label: {
          Image(systemName: "magnifyingglass")
        })
      }
    }
  }
}

Selecting a route in the first time works, but when going back to the List and selecting a different route, the state updates twice. First to the new state and there's an update immediately after to the previous state.

Here's what's happening on video: https://streamable.com/a3kgnu

What am I doing wrong?