Every time I fork a repl it re-upgrades to the Nix package

I am using repl for a software engineering bootcamp, so I am constantly having to fork repls for small exercizes, yet every time I do it redoes the upgrading process which can be time consuming. Anyone know a fix?
Does repl upgrade per project?

You are probably forking a non-Nix Repl. Try creating a fork from the non-Nix Repl, let it upgrade, then fork the upgraded version whenever you want to fork.