In my opinion the worst and most distinguishable downside of webp is the forced 4:2:0 chroma subsampling. On many images with bright colors you can clearly see the color and brightness loss without an educated eye.
On comparison [1] you can clearly see that the top right balloon has lost its vibrant red color. On comparison [2] the bright blue neon art on the center has lost its brightness.
On comparison [1] you can clearly see that the top right balloon has lost its vibrant red color. On comparison [2] the bright blue neon art on the center has lost its brightness.
[1] https://storage.googleapis.com/demos.webmproject.org/webp/cm...
[2] https://storage.googleapis.com/demos.webmproject.org/webp/cm...