title: UITextField has different background on TestFlight and mac output
body: <p>Recently I deploy my app on TestFlight for inner test.
  I found UITextFields on my app has different background colors on TestFlight and directly output by my mac.</p>
  <p>Is it just a TestFlight bug? Or an iOS version difference?</p>
  <p><a href="https://i.stack.imgur.com/C8Ufr.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/C8Ufr.jpg" alt="attached 1: directly output by my mac." /></a></p>
  <p>attached 1: directly output by my mac. User: iOS 14.4.2</p>
  <p><a href="https://i.stack.imgur.com/ou1e7.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ou1e7.jpg" alt="enter image description here" /></a></p>
  <p>attached 2: on TestFlight. Users: iOS 14.4, iOS 14.5.1</p>
  <p>I've checked the code. Nothing is different. At least I didn't find difference.</p>