You may have encountered a "new" image format known as WebP. It's been around for about a decade, and was created by Google. Today it is used by many websites.
The annoying thing you will discover (if you don't already know) about the WebP format is that it is not supported by many proletterimage editors. So when you download a WebP image, you probably won't be able to edit it. Of course you can't save it in some other format directly.
Recently, a plugin called Save WebP as PNG or JPEG (Converter) was released. The extension is very useful because it converts and saves WebP images to some editable format and resolutions.
Once installed, in Firefox you can find it if you turn right click on a WebP image as shown below
Select Save WebP as or Save WebP as and many options will appear to the left of the image.
You can choose the format you want to save the image, as well as (PNG, JPG, GIF) but also the quality (100/92/85/80/75%) of the JPG format.
I again save it with a right click and change the ending to jpg… am I doing something wrong ??? Because even so, it saves them fine… ..
in some it can be done, in others again not whatever ending you put