That screenshot looks like you're loading the desktop site on a phone. In this case I think that's triggering text auto resizing which has made the body text large but left the code text very small.

When looking at the site in mobile mode or desktop it does seem better. I do agree that many sites use font sizes that are too small these days though.

With Firefox on an actual desktop it looks fine, code fontsize matches text size

I felt the need to disagree because a lot of these "font is too small" complaints seem to be advocating for people using larger font sizes in general. Which I would prefer not to see, default font sizes are already large enough