The funny thing there is that prettifyCode.js looks to be attempting to set the scene for a client-side highlighter, but no such highlighter is then used. And you’ve already got server-side highlighting happening.
Yeah, this is very likely an artefact of switching my blog from Django to Jekyll years ago, and then adopting rouge years after that. I definitely would like to use less JS on my website, and like you said, I already have server-side highlighting.