title: Backdrop filter not working when mix blend mode of another element on the page is changed
body: <p>The browser version is Chrome 87.0.4280.88</p>
  <p>Here is how I accidentally detected this bug:</p>
  <blockquote>
  <ul>
  <li>There are two independent divs on the page and both are <code>position: fixed;</code></li>
  <li>One of them has a hover effect with which its <code>mix-blend-mode</code> is changed.</li>
  <li>The other one has glassmorphism style on it with <code>backdrop-filter: blur(...px);</code></li>
  <li>The filter works only when the other element on the page is set to <code>mix-blend-mode: normal;</code> otherwise it looks like as if it was not supported.</li>
  </ul>
  </blockquote>
  <p>I am going to quit using that hover effect for now anyway but if there is a trick then it would be nice to let the world know about it.</p>