A possible SwiftUI bug?

ABCBug.swift

//
//  ContentView.swift
//  ABCBug
//

/*
 Is this a bug?
 
 Why does pressing the button change
 the "outer" value and not the "inner" value?
 */

import SwiftUI

struct InnerContentView: View {
  @State var number: Int
  
  var body: some View {
    Text("Inner: \(number)")
          .padding()
  }
}

struct ButtonView: View {
  @Binding var number: Int
  
  var body: some View {
    Button("Change to 2"){ number = 2 }
  }
}

struct ContentView: View {
  @State var number = 0
  
  var body: some View {
    VStack {
      InnerContentView(number: number)
      Text("Outer: \(number)")
            .padding()
      ButtonView(number: $number)
    }
  }
}

struct ContentView_Previews: PreviewProvider {
  static var previews: some View {
    ContentView()
  }
}