@SuperDicq The fork functionality on GitHub works like a tree. If you have a fork of a repository and that fork lost its parent because it was deleted, that fork is now the parent of the tree. If you private a repo, all the previously public code can still be accessed from the forks and if you delete that private repo every public fork will still work.

If you have a private repo and make it public, all the commits in the private repo are now public. The only thing you need is the commit hash to access them.

There was a big kerfuffle about exactly this issue few months back.

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/what-happens-to-forks-when-a-repository-is-deleted-or-changes-visibility#changing-a-public-repository-to-a-private-repository
https://trufflesecurity.com/blog/anyone-can-access-deleted-and-private-repo-data-github