NavigationLink automatically pop

Xcode Version 13.2.1 (13C100) iOS15.2 Swift5 If repeat the navigation about 10 times, it will return FirstView automatically. The expected output is to move from 0 to 100 with the next button.

I am developing a list navigation app with SwiftUI. A navigation bug occurred in the code and procedure shown below. 1.tap item in FirstView. 2.open SecondView. 3.open ThirdView. 4.tap next button navigate to SecondView. Repeat steps 2-4 about 10 times navigate SecondView when pop View to FirstView. How can I solve it?

import SwiftUI

final class ViewModel: ObservableObject {
    @Published var currentIndex: Int?
    
    public func next() {
        if let currentIndex = self.currentIndex {
           if currentIndex < 100 {
               self.currentIndex = currentIndex + 1
           } else {
               self.currentIndex = nil
           }
        }
    }
}

struct FirstView: View {
    @StateObject var vm = ViewModel()
    
    var body: some View {
        NavigationView {
            List(0..<100) { i in
                NavigationLink(String(i),
                               tag: i,
                               selection: $vm.currentIndex) {
                    SecondView(vm: vm)
                }.isDetailLink(false)
            }
        }
        .navigationViewStyle(StackNavigationViewStyle())
        .navigationTitle("First View")
    }
}

struct SecondView: View {
    @ObservedObject var vm: ViewModel
    
    var body: some View {
        VStack {
            NavigationLink("go to third") {
                ThirdView(vm: vm)
            }.isDetailLink(false)
            
            if let currentIndex = vm.currentIndex {
                Text("currentIndex: \(currentIndex)")
            }
        }
        .navigationTitle("Second View")
    }
}

struct ThirdView: View {
    @ObservedObject var vm: ViewModel
    
    var body: some View {
        VStack {
            Button(action: vm.next) {
                Text("next")
            }
            if let currentIndex = vm.currentIndex {
                Text("currentIndex: \(currentIndex)")
            }
        }
        .navigationTitle("Third View")
    }
}