Seconding this. It feels like every other day I download an image, realize it's WebP and start bashing my head against the desk because it means opening it in GIMP to convert it to JPEG once again.
I've got several hundreds of GB of unused SSD storage, and I'm downloading it over a 1Gbps connection. Honestly, I really could not care less about those 150KB I'm saving.
I tried to use it for a screenshot in a README on GitHub, and raw.gitusercontent.com couldn't serve the right MIME type. I was surprised. PNG it is, then.
So not only browser support, but server support. (Which is really easy to support.)
We need a website like caniuse.com that tracks support for file formats on operating systems and software. I would be interested to see the support of WebP out of the box on Windows 11, macOS, Ubuntu, stock Android, iOS, the GIMP, Adobe Photoshop, and so on.
"And so on" would have to cover too many different software. And then there's random devices like smart picture frames that still won't support non-traditional formats.
I've got several hundreds of GB of unused SSD storage, and I'm downloading it over a 1Gbps connection. Honestly, I really could not care less about those 150KB I'm saving.