The "This is the key insight -" or "x is where it gets practical -", are dead give aways too. If I wanted an LLMs explanation of how it works, I can ask an LLM. When I see articles like this I'm expecting an actual human expert

I imagine it's not the AI then, but the site font/css/something. Seeing as it looks fine for me (Brave, Linux).

Are you on a phone? I loaded the article with both my phone and laptop. The ascii diagram was thoroughly distorted on my phone but it looked fine on my laptop.

I found it more jarring that they chose to use both Excalidraw and ascii art. What a strange choice.