As of version 9.1, Drupal automatically lazy-loads images by default. This functionality adds a
loading="lazy" attribute when outputting an
<img> tag. When the browser sees this, it will not download the image until it enters the viewport. This can save your user (and your web host) gobs on bandwidth by not downloading images that will never be used.
Notes on Awesomizing Drupal's Editor's Backend
Notes from SEO and Drupal: Best Practices and Tools