The site claims to be using https://fonts.google.com/specimen/EB+Garamond but something has gone wrong with the italics (at least on my screen), they are just an oblique version of the roman version of the font, whereas the Google Fonts page has a much nicer actually italic version (e.g. compare the lowercase h on the Google Fonts page above vs the linked page).
I’m seeing the same thing. Sorts Mill Goudy also comes in a single weight and it looks like the author is forcing CSS font-weight values beyond 400 for their headings.
Off-topic: I think UX blogs give me the heebie jeebies.
This reaction isn't targeted toward all UX blogs...but some of the one's that I've come across go a little too far with their rhetoric. Some of them have this overt "romanticist" bend to them that can come across as overblown from a user's perspective. The constant appeals toward aesthetic ("beauty, elegance") and emotion ("sparking joy") put me off.
I don't mean to downplay the effects that good and bad UX design have on people. It matters, but where it matters most (rental property portals, banks, healthcare industry, etc.) is where things like "beauty" and "joy" matter the least. This leads me to question the type of software, web pages, etc. that these sort of designers/bloggers are speaking on behalf of and how these kind of blogs run parallel to other hand-wavy bodies of writing authored in the tech industry, or any other industry for that matter.
Granted, there's nothing wrong with aesthetic appeals and the like, but if you're going to make one it shouldn't sound like a Steve Jobs WWDC keynote speech generated by Bard. I feel like there's an intangible quality to expressions on aesthetics in a way (although most of the time there are identifiable reasons for their appeal if you think hard enough). Some UX blogs lack that.
