This seems to fit the pattern: websites about typography play with typography until it's broken, those about web design in general are more likely to not render well in older or simpler web browsers, and those about security are more likely to fail even on the TLS handshake stage due to overly enthusiastic cipher suite restrictions.

Reader mode is commonly suggested to deal with it, and one can configure FF (possibly other web browsers too) to always work in a similar way by disallowing web pages to change fonts and by setting a minimal font size. Combined with a global CSS to set colours (another step towards reader mode), it makes most texts on websites legible, as long as they don't mess with finer font rendering settings.

The website looks really beautiful on my screen. Probably a question of screen resolution? It is true that many serif typefaces degrade quickly on lower resolution displays.

Yeah, same issue here. Kinda ironic writing a blog about typography but chosing such a terrible font to read on a display. I would bet that the writer is a mac exclusive user and it only looks good on mac due to some random quirk of macos

Looks good for me.

On a big phone it is really comfortable.