I put in my site and it gave me a red cross for "Hosting", on hover it said "GitHub Pages". But my site isn't hosted on GitHub Pages.

Expanding "Details", the URL that is hosted on GitHub Pages is... a different website? There's merely a hyperlink to it on my website.

It also says I'm using "self-hosted" fonts - but I don't think I'm doing that at all? I'm just using the browser's fonts. Using non-standard fonts is a bad idea because it causes the content to either be invisible until the font is loaded, or else it initially shows in a fallback font and then the text all jumps when the font is loaded.