Thanks - I downloaded that zip file (460MB!) and extracted one of the examples into a Gist: https://gist.github.com/simonw/5a8054f18f9ea3c560b628b16b00f...
Here's an original: https://gist.githubusercontent.com/simonw/5a8054f18f9ea3c560...
And the jpegli-q95- version: https://gist.githubusercontent.com/simonw/5a8054f18f9ea3c560...
And the same thing with mozjpeg-a95 https://gist.githubusercontent.com/simonw/5a8054f18f9ea3c560...