Remember though that butter is only 80% fat. Especially relevant for baking recipes where you have a ton of butter and if you replace that can make it denser and greasier. E.g. 200g butter you should replace with ~160g oil and 40ml water.

That is exactly what’s happening :) better quantization matrix results in 25% smaller files with the same perception-based q which makes webo kinda useless https://siipo.la/blog/is-webp-really-better-than-jpeg

Try jpeg-xl though. it’s amazing.