dismiss() not work sometimes

[Project112224]

Repeat operation present and dismiss (View Controller button)，but dismiss sometimes not work，touch other element can't any action，

with example project
in DemoViewController.swift / class ViewController / viewDidLoad() add code

let button = UIButton(frame: CGRect(x: 0, y: 0, width: 50, height: 50) )
button.setTitle("tttt", for: .normal)
button.addTarget(self, action: #selector(self.tttt), for: .touchUpInside)
self.view.addSubview(button)

and function

@objc func tttt() {
    self.dismiss(animated: true, completion: nil)
}

console only show

Will dismiss dismiss by nil
Did dismiss dismiss by nil
Will dismiss dismiss by nil

use ios 14.8.1，iphone SE

I missing something?
Any answer help me.
Thanks.