Currently, not all web browsers are compatible with the WebP format.
Thanks to the update of iOS 14 in November 2020, most major web browsers allow you to view WebP images. But Internet Explorer and the old version of Safari (iOS 13 or earlier) do not.
An animated WebP image requires higher CPU usage than a GIF image does.
The decoding of a lossy WebP image takes 2.2 times longer than that of a GIF image does. If the image is lossless-compressed, it takes 1.5 times longer.
Many websites have no support for uploading a WebP image yet.
The conventional image formats including GIF, JPG, and PNG were developed a long time ago, and they are well-supported on almost all websites. But uploading a WebP image is not available on quite a number of websites yet.
There are not many image editor programs compatible with the WebP format.
Honeycam is one of the rare editor programs which allows you to edit animated images and save them as WebP files.