swift – `.navigationBarBackButtonHidden()` not engaged on iOS 18.4

I’ve received a minimal reproducible instance of DocumentGroup app utilizing a NavigationSplitView with a DetailView. I need to utterly take away the default Navigation Bar inside these views and provide my very own .toolbar. That is how I achieved this on iOS 18.0-18.3

App.swift

@foremost
struct App: App {
    var physique: some Scene {
        DocumentGroup(newDocument: BackButtonTestDocument()) { file in
            NavigationSplitView {
                Record {
                    NavigationLink("Element View", vacation spot: DetailView())
                }
            } element: {
                DetailView()
            }
            .toolbar(.hidden, for: .navigationBar)
        }
        DocumentGroupLaunchScene("Again Button Check") {
            Coloration.inexperienced
        }
    }
}

DetailView.swift

struct DetailView: View {
    var physique: some View {
        VStack {
            Textual content("That is the element view")
        }
        .navigationBarBackButtonHidden(true)
        .toolbar {
            LightbulbButton()
        }
    }
}

LightbulbButton.swift

struct LightbulbButton: ToolbarContent {
    var physique: some ToolbarContent {
        ToolbarItem(placement: .topBarLeading) {
            Button(motion: { print("Tapped") }) {
                Label("Lightbulb", systemImage: "lightbulb")
            }
        }
    }
}

This code received me the outcome I wished:

Nonetheless this conduct appears to interrupt on iOS 18.4. I can repair the primary display screen by shifting the .toolbar(.hidden) modifier up contained in the NavigationSplitView. However I can not seem to discover a strategy to get .navigationBarBackButonHidden(true) to work. Or to override the default navigation bar generally

How can I successfully override the default Navigation Bar with a customized button format in iOS 18.4 and onwards?

I’ve tried shifting the navigationBarBackButtonHidden(true) modifier to a number of locations however this modifier simply does not appear to work in any respect. Even when it did, I might nonetheless be caught with the title and the title bar menu.