It's funny, the author says the high contrast hurts his eyes, but for many visually impaired users (myself included), light mode is like a blinding white light that's very hard to look at while dark mode is very comfortable while still having high contrast.

IMO every website should have a native dark & light mode theme. There is a browser extension, Dark Reader, which changes the CSS to force dark (or light) mode but it can be really hit or miss depending on how the site was coded.