Google invented .webp to save corporations lots and lots of bandwidth with the new reduced image size. Technically it's the choice of the site host to distribute images as .webp so Lemmy is a bit guilty as well for adopting the standard. I don't like Webp, for some reason they don't get treated as image files when you try to visit their source or open them in a windows file structure, instead it takes you to some shitty bloated webpage with more than just the image.