When I use just the file name or a supported extension, it successfully returns the image. But if I use the .avif extension, which is the latest (and best?) image format in the web currently (the only downside of it is browser support and that is easy to get over it with picture tag), it redirects it to original URL.
https://cdn.statically.io/img/www.lifemcserver.com/lib/img/slider1 --> success, serves JPEG image (I don’t know if this statically’s choice or I have a .htaccess rule, doesn’t matter anyway)
cdn.statically. io/img/www.lifemcserver.com/lib/img/slider1.webp -> success, serves WebP image
cdn.statically. io/img/www.lifemcserver.com/lib/img/slider1.avif -> failure, redirects with 301
(ommitted the https and placed a space before domain extension on last two links because it said new users can only put two links)
I also tried an invalid extension to make sure that AVIF is not supported or it is just doing the thing you said in here: Seeing redirect to image source rather than cacheing
And I think it just redirects invalid extensions to original URL. Treats AVIF as same as invalid extensions since it doesn’t recognize as an image format extension, I think.