onAppear modifier called twice when applying .navigationViewStyle(.stack) on NavigationView

Question

[Summarize the problem]

.onAppear modifier called twice when using .navigationViewStyle(.stack) on NavigationView.

[Describe expected and actual results]

I am expecting .onAppear to be called once but .onAppear is called twice.

EDIT: I Removed the link to the project and added a much simpler template code showing the issue.

import SwiftUI

struct RootView: View {
    
    @State private var showDestinationView = false
    
    var body: some View {
        NavigationView {
            LeftView()
            
            NavigationView {
                NavigationLink(isActive: $showDestinationView) {
                    DestinationView()
                } label: {
                    Button("Show Destination") {
                        print("didPressButton")
                        showDestinationView = true
                    }
                }
            }
            .navigationBarTitle("Title")
            .navigationViewStyle(.stack) // Without this line, onAppear is called once.
        }
    }
}

struct DestinationView: View {
    var body: some View {
        Text("Destination View")
            .onAppear {
                print("onAppear")
            }
    }
}

struct LeftView: View {
    var body: some View {
        VStack {
            Spacer()
            
            Text("Left")
            
            Spacer()
        }
        
    }
}

And here are the logs:

didPressButton
onAppear
onAppear