So Ive checked and its enabled, even did a GD PHP dump and Avif support is true.
But I note in another post you said “Even if turned on by your provider, it still wouldn’t work because it is not supported by SimpleImage, the library used by Kirby’s GD driver”
Maybe I’m better off just using Webp as standard, the only thing for me is that when using the standard GD driver and webp, it compresses the .webp images so that they are almost unusable and this is with ‘quality’ => 90, in my config file.