Swift wkwebView中显示两个进度 问题

当我第一次使用以下代码加载WebView时，进度条工作正常，但当我在WebView中单击链接时，似乎看到两个进度条

class DetailViewController: UIViewController {
    
    private var wkWebView: WKWebView!
    
    let progressView = UIProgressView(progressViewStyle: .default)
    
    private var estimatedProgressObserver: NSKeyValueObservation?
    
    override func viewDidLoad() {
        super.viewDidLoad()

        setupWebView()
        load()
        setupProgressView()
        setupEstimatedProgressObserver()
    }
 


    func setupWebView() {
        let webConfig = WKWebViewConfiguration()
        wkWebView = WKWebView(frame: .zero, configuration: webConfig)
        wkWebView.uiDelegate = self
        wkWebView.navigationDelegate = self
    }


    private func setupProgressView() {
        guard let navigationBar = navigationController?.navigationBar else { return }

        progressView.translatesAutoresizingMaskIntoConstraints = false
        navigationBar.addSubview(progressView)

        progressView.isHidden = true

        NSLayoutConstraint.activate([
            progressView.leadingAnchor.constraint(equalTo: navigationBar.leadingAnchor),
            progressView.trailingAnchor.constraint(equalTo: navigationBar.trailingAnchor),

            progressView.bottomAnchor.constraint(equalTo: navigationBar.bottomAnchor),
            progressView.heightAnchor.constraint(equalToConstant: 2.0)
        ])
    }
    
    private func setupEstimatedProgressObserver() {
        estimatedProgressObserver = wkWebView.observe(\.estimatedProgress, options: [.new]) { [weak self] webView, _ in
            self?.progressView.progress = Float(webView.estimatedProgress)
        }
    }
}


// MARK: - WKNavigationDelegate
extension DetailViewController: WKNavigationDelegate {
    
  
    // 読み込み準備開始
    func webView(_ webView: WKWebView, didStartProvisionalNavigation navigation: WKNavigation!) {
        if progressView.isHidden {
            progressView.isHidden = false
        }

        UIView.animate(withDuration: 0.33, animations: {
            self.progressView.alpha = 1.0
        })
        print("読み込み準備開始")
    }

    // 読み込み完了
    func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
        UIView.animate(withDuration: 0.33,
                       animations: {
                           self.progressView.alpha = 0.0
                       },
                       completion: { isFinished in
                           self.progressView.isHidden = isFinished
        })
        print("読み込み完了")
    }
}

这里怎么了？谢谢你的帮助

环境

• 迅捷5
• iPhone SE（第二代）11.6版（921.9.1）
• 代码11.6