Storing anything at all in the windows registry is somewhat bad practice, but using it for large amounts of runtime data, AND not even deleting it afterwards or managing it correctly. Wow. That is some grade A+ premium bad practice spaghetti I would get second hand embarrassment from seeing in a 24 hour gamejam codebase. My only hope is that whichever developer wrote this was either extremely sleep deprived or didn't read the documentation for the PlayerPrefs API and just guessed what it did from function names alone. Even then something called "PlayerPrefs" should be a red flag if you're aiming to store anything other than player preferences.
I am both confused and utterly shocked someone wrote this in a production videogame.