Bug Description

We already got a fix at #288 by @mitogh for the featured images - thanks for that! Some time ago i developed a small simple website with gutenberg & generatepress. i tried to use as many default blocks as possible. Some elements are working with the webp replacement as expected - some not yet.

generatepress offers a container block. it allows to choose a image from the library and sets its url into the field

the background image is set over css and currently not replaced by a webp image - although one would be available

This currently seems to be the only issue left on my testpage where webp images dont get automatically choosen.

Steps to reproduce

1. Upload jpeg images - implement them as background images over css
2. install performance plugin, activate webp
3. use Regenerate Thumbnails plugin to generate the web
4. See on frontend if they get used as webp or still jpg

Additional Context

• PHP Version: 8.0
• OS: Windows
• Browser: MS Edge
• Plugin Version: Version 1.2.0