Navigation View inside Tabview No issue in portrait mode In landscape mode, navigation view and all subviews are "collapsed" into a top-level menu. See screen shots below.
Is it normal behaviour? Could not find any modifier to change this behaviour if it is normal.
Portrait mode
Landscape mode
Landscape mode after clicking top left menu
Test project showing issue:-

TabView {
    ChartView().tabItem {
        Label("Chart", systemImage: "chart.bar")
    }
    Page1View().tabItem {
        Label("Received", systemImage: "tray.and.arrow.down.fill")
    }
}

body of Page1View struct:-
var body: some View {
    NavigationView {
        VStack(spacing: 10) {
        // ... removed for clarity
        }
        .toolbar {
            ToolbarItem(placement: .navigationBarLeading) {
                Text("tbar1")
            }
            ToolbarItem(placement: .navigationBarTrailing) {
                Text("tbar2")
            }
            ToolbarItem(placement: .navigationBarTrailing) {
                Text("tbar3")
            }
        }
    }
}