Note that Statically uses multi-CDN, so to give you insights to help you predict, here’s how WebP works at Statically:
– Fastly: will send WebP if accept: image/webp
header present no matter what, even if the image gets large (yes, converting JPG to WebP can result in a large file size)
– BunnyCDN: same as Fastly
– Cloudflare: will check the WebP file size is larger than the original image, if not, then send
I personally prefer the approach applied in Cloudflare, because it’s faster, therefore a larger portion of the traffic is currently going to Cloudflare, they also provide more PoPs for Statically. You can check the DNS resolution for cdn.statically.io from around the world at https://dnschecker.org/#CNAME/cdn.statically.io and see what you got.
WebP is great, but the web is getting modern, modern solutions have to be made, edge logic is getting more advanced and static asset delivery has to be smarter. Serve WebP only when it is useful to serve.
Again, this is a challenge running the auto-WebP service with a multi-CDN and this is what we can make.
If you want something like always-WebP, I recommend that you go with a paid solution, there are many services that provide this.
Quoting @gijo “Converting all images to WebP is not always good”.