If you don't mind using an online service, then EzGif.com is a good alternative as well, and it supports animated WEBP images to Animated GIF.

WebP is a modern image format that provides superior lossless and lossy compression for images on the web

I honestly do not know if this really is the case, but I do know it is annoying that most graphics applications (at the time of writing this) do not support the WEBP file format.

There are several methods to convert a WEBP file to something useful, for example online converters, and some desktop applications.
But there is a method that works straight from the command line (Terminal, DOS, Linux Shell) by using the Webp-tools from Google from here.

Select the one suitable for your OS, and extract the file.

You will find a tool in the archive called "dwebp" (in the bin directory), which "Decodes the WebP image file to (default) PNG format" as such:

./dwebp -o output.png input.webp

The tool also supports output as PAM (raw RGBA), PPM (raw RGB), BMP, TIFF, PGM and YUV.

If you would prefer for example BMP, then this can be doen as such:

./dwebp -bmp -o output.bmp input.webp

I'm not sure if this will work under Windows or Linux, but under MacOS I found that I can just copy the file (dwebp) to any location, and it doesn't seem to need any of the other files.