There are some interesting issues that probably relate to your workflow, like the nav links are different sizes, the icons too. And the resolution of some of the images/icons on a MacBook is poor. But I suspect that's because a simple ImageMagick raster diff will fuzz over those kind of differences.

I wonder if you can make some tweaks or find a better representation than pure raster screenshots to fix this. Can't really deal in vector images because AI sucks at outputting those, and you can't print a web page to SVG.

There was a super niche website framework that only used SVG a while ago. Would be funny if that kind of thing makes a takes off just so AI can do better.