There are a few questions that mention this warning, but no general solutions or simple examples.

The following code has a main view and a subview with a text field. When clicking the “return” button on the subview, the following warning shows up:

Publishing changes from within view updates is not allowed, this will cause undefined behavior.

struct MainView: View {
    @State var showSubView = true
    
    var body: some View {
        ZStack {
            if showSubView {
                SubView(showSubView: $showSubView)
            }
        }
    }
}

struct SubView: View {

    @Binding var showSubView: Bool
    @State var text: String
        
    var body: some View {
        VStack {
            
            TextField("", text: $text) // Removing this line removes the warning
            
            Button("Return") {
                showSubView = false
            }
        }
    }
}

The odd part is that when the TextView is removed, this warning doesn’t happen, even though text is not linked to MainView. Why is this error happening? Why does adding a TextView cause it?