This site probably shouldn't measure via Software Heritage. They aim to preserve full histories of repos. Limited mainly to GitHub, plus some approved others.
It's not an attempting to discover/crawl every self hosted repo. You can move to Forejo, and delete your GH, they'll still have a copy of your GH, no deduping, and never find your Forejo.
It includes thousands of mirrors and former repos under github/wikimedia. Harmless for preservation. But as a metric?