I checked a couple past posts and they have the same canonical link issue (on your site). But HN only recently started rewriting URLs to the canonical links if they were in the HTML so it's likely that it was just a non-issue (on HN) before today.
Neat article, by the way, and it has prompted me to get back to finishing Nand2Tetris.
Not sure what's happening, but that's the present link on HN. It should be:
https://www.philipzucker.com/nand2tetris-chc/
EDIT: Canonical link issue:
There's a typo there, causing HN to rewrite it as the first link.