In a blog post, when a jpg image in the post is set as the cover image, it is replaced by Wix with a webp image format when the blog post is displayed on the Wix website. This may either reduce or increase the weight of the image file. However, in the blog-feed.xml file, the rss enclosure image type is png. This greatly increases the image file weight and impacts performance when the blog post is rendered from the rss feed.
Please explain this substitution of file formats, especially conversion to the png format in the rss feed.