Test of TimerPublisher in SwiftUI

TimerTest.swift

import SwiftUI
    
struct TimerTest: View {
    @State var date = Date()
    @State var showSubView = false
    @State var timer: Timer?
    @State var date1 = Date()
    @State var timer1 = Timer.publish(every: 1, on: .main, in: .common).autoconnect()
    
    var body: some View {
        ZStack{
            if showSubView {
                VStack {
                    Text(" Timer Stoped?")
                    Button("Back") {
                        self.showSubView = false
                    }
                }
            }
            else {
                VStack {
                    Button("Switch to subview"){
                        self.showSubView = true
                    }

                    Text("date: \(date)")
                        .onAppear(perform: {
                            self.timer = Timer.scheduledTimer(withTimeInterval: 1,
                                            repeats: true,
                                            block: {_ in
                                              self.date = Date()
                                              NSLog("🔷onAppear timer triggered")
                                             })
                        })
                        .onDisappear(perform: {
                            self.timer?.invalidate()
                            self.timer = nil
                            NSLog("🔶 onDisappear stop timer")
                            // But if I close window, this method never be called
                        })
                    
                    Text("date1: \(date1)")
                        .onReceive(timer1) { currentTime in
                            self.date1 = currentTime
                            NSLog("🔴 onReceive timer1 trigger")
                        }
                        
                        // In theory, onReceive(timer1) is work well when window close, or just the view disappear
                        // But, when View switch back from the subview, timer1 won't be resume
                        // So I have to reinstance a new TimerPubliser onAppear.
                        .onAppear(perform: {
                            self.timer1.upstream.connect().cancel()
                            self.timer1 = Timer.publish(every: 1, on: .main, in: .common).autoconnect()
                        })
                        .onDisappear(perform: {
                            NSLog("🔴 onDisappear timer1 auto stop (only when the view switch, but not called when window closed)")
                        })
                }
            }
        }
        .frame(width: 500, height: 300)
    }
}

但是我还无法理解 TimerPublisher 怎么做到的自动停止？
按照 apple 的官方文档，Timer 是被 RunLoop 强引用的，生成 TimerPublisher 的时候，就定义了一个 Timer， 通过 on: .main 参数这个 Timer 关联到主线程的 RunLoop。
那 TimerPublisher 它自己呢？ 是放在哪里管理？ 为什么视图切换，窗口关闭都能引起 TimerPublisher 停止？（可能 Timer 并没有停止，只是 Publisher 停止了）