StateObject unexpectedly init twice

Environment (Simulator & Device):

• iOS 17.5.1
• iOS 16.7
• iOS 18.0 beta 3

Steps to Reproduce:

1. Build and run
2. On the main screen, tap “First”.
3. Then tap “Second”.

Observed Behavior:

• On iOS 17.5.1, the StateObject attached to DetailView is initialized twice. The expected behavior is that the StateObject should be initialized only once.
• On iOS 16.7, the StateObject is initialized only once, as expected.
• On iOS 18.0 beta 3, the StateObject is initialized only once initially. However, if you swipe down to dismiss the DetailView, the StateObject is unexpectedly initialized again.

Expected Behavior:

• The StateObject should be initialized only once, and should not be reinitialized when dismissing the DetailView.

Please investigate this issue. FB14283951

import SwiftUI
 
class Object: ObservableObject {
    @Published var flag = false
    init() {
        print("object init")
    }
}
 
struct DetailView: View {
    @StateObject var object = Object()
    
    var body: some View {
        Text("\(object.flag)")
    }
}
 
struct ContentView: View {
    @State var showingFirst = false
    @State var showingSecond = false
    
    var body: some View {
        NavigationStack {
            ZStack {
                Button("First") {
                    showingFirst = true
                }
                .sheet(isPresented: $showingFirst) {
                    NavigationStack {
                        // replace this ZStack with Form, List, issue exists.
                        // remove this ZStack, issue gone.
                        ZStack {
                            Button("Second") {
                                showingSecond = true
                            }
                            .sheet(isPresented: $showingSecond) {
                                DetailView()
                            }
                        }
                    } // 2nd NavigationStack
                } // 1st sheet
            } // ZStack
        } // 1st NavigationStack
    } // body
} // ContentView