You gave me very little to go by!
But I now recognize the first screenshot is from the Cache Enabler plugin. The WebP functionality of the Cache Enabler plugin works serving modified HTML to browsers that supports webp. It however only modifies the HTML for those images, where it finds an image with the “.webp” extension in the same folder as the original image. WebP Express stores all the converted images in a separate folder, so they are unfortunately not picked up by the Cache Enabler plugin.
The good news is that it is on the WebP Express roadmap to optionally store the converted images in the same folder as the originals: https://github.com/rosell-dk/webp-express/issues/104
