OP is a photographer and is pretty clear about that being part of their motivation:
> Stick to JPEG at 90 quality (or at least 85) if images matter to you, e.g. if you are a visual artist. If images are pretty decorations for your textual content, it doesn’t matter.
That's the whole point of compressing the image, isn't it?
To me, it looks like webp does its job.