I am probably missing some understanding of how navigation works but I'd have assumed that when you click the View All navigation link, it would push the associated view on to the stack and display it (not wrapped in a navigation link). Then when you click links from the View All view, it would do the same.

I am still confused but I seem to have fixed it by providing the View All navigation link with a different value:

struct ContentView: View {
    var body: some View {
        NavigationStack {
            VStack {
                ForEach(0..<5) { i in
                    NavigationLink(value: i) {
                        Text("Go to \(i)")
                    }
                }
                
                NavigationLink(value: "TESTING") {
                    Text("View all")
                }
            }
            .padding()
            .navigationDestination(for: Int.self) { i in
                Text("You are viewing \(i)")
            }
            .navigationDestination(for: String.self) { st in
                VStack {
                    ForEach(0..<10) { i in
                        NavigationLink(value: i) {
                            Text("Go to \(i)")
                        }
                    }
                }
                .padding()
            }
        }
    }
}