It also says my website is hosted on GitHub pages, although it’s served from a hetzner server.

EDIT: on further inspection: I get both a red cross AND a green check mark for hosting. So it’s somehow indicating both GitHub and hetzner. Maybe it’s because I merely link to GitHub?

Fixed. I was matching a link TO GitHub as hosting ON GitHub. Now only embeds and actual hosting count, not href links.

Sorry and thanks for pointing me there.