iOS 15: navigationBarHidden(true) no longer working after display of another view

In iOS 15 beta (still occurring with beta 4), navigationBarHidden(true) is no longer working if a navigation view with the .navigationViewStyle(.stack) modifier is displayed after a view that is not a NavigationView.

class SelectorHelper : ObservableObject {

    @Published var show_intro : Bool = false

}

struct myApp: View {

    @ObservedObject var selector_helper : SelectorHelper

    var body: some View {

        if selector_helper.show_intro == true {

            intro(selector_helper: selector_helper)

        }

        else {

            app_content(selector_helper: selector_helper)

        }

    }

}

struct intro: View {

    @ObservedObject var selector_helper : SelectorHelper

    var body: some View {

        VStack {

            Spacer()

        Text("Intro")

            Button(action: {

                selector_helper.show_intro.toggle()

            }){

                Text("Show content")

            }

            Spacer()

        }

        .background(.yellow)

    }

}

struct app_content: View {

    @ObservedObject var selector_helper : SelectorHelper

    var body: some View {

        NavigationView {

        VStack{

            Spacer()

        Text("App Content")

            Button(action: {

                selector_helper.show_intro.toggle()

            }){

                Text("Show intro")

            }

            Spacer()

        }

        .background(.green)

        .navigationBarHidden(true)

        }

        .navigationViewStyle(.stack)

    }

}

iOS 15: navigationBarHidden(true) no longer working after display of another view
 
 
Q