I was trying to upload a webp  image as the main image and i get this error

Unsupported file format (FF002)

anchorpackof4.webp

The file is not supported by eBay. Please remove it and upload only JPG, GIF, PNG, TIF or BMP files.

eBay doesn't support webp images to be uploaded which are smaller and clearer.

They are however allowed in the html description of the auction.