Why 'keyboardWillShowNotification' is fired when background taped in iOS 14?

Why in iOS14 (or at least iOS14.4.1 iPhone X) keyboardWillShowNotification is fired when background(UIScrollerView) taped, while in iOS13 is not?

I am trying to run a function when the keyboard shows and disappears, have the following code:

import UIKit
class ViewController: UIViewController {
    @IBOutlet weak var scrollView: UIScrollView!
    @IBOutlet weak var textField: UITextField!
    let notificationCenter = NotificationCenter.default    

    override func viewDidLoad() {
        super.viewDidLoad()        

        notificationCenter.addObserver(self, selector: #selector(keyboardWillShow), name: UIResponder.keyboardWillShowNotification, object: nil)

        notificationCenter.addObserver(self, selector: #selector(keyboardWillHide), name: UIResponder.keyboardWillHideNotification, object: nil)
    }    

    deinit {
        notificationCenter.removeObserver(self)
    }

    @objc private func keyboardWillShow(_ notification: Notification) {        updateBottomLayoutConstraintWithNotification(notification: notification, bottomConstraint: nil, tag: "keyboardWillShow()")
    }

    @objc private func keyboardWillHide(_ notification: Notification) {        updateBottomLayoutConstraintWithNotification(notification: notification, bottomConstraint: nil, tag: "keyboardWillHide()")
    }    

    func updateBottomLayoutConstraintWithNotification(notification: Notification, bottomConstraint: NSLayoutConstraint?, tag: String = "") {
        print("[Caller Name] \(tag)")
    }
}

Operation steps

1. Tap the textField(Keyboard Raised)
2. Tap the background(UIScrollerView)

Such a log will be generated

[Caller Name] keyboardWillShow()
[Caller Name] keyboardWillShow()

Thank you for your attention!