Are you saying GH has more than Codestral and therefore GH has a better model? Or that Codestral would be better because Codestral is not littered with "bad" code?
Bad code is obviously very subjective, but I would wager that GH places a much higher value on feedback mechanisms like stars, issues, PRs, velocity, etc. Their ubiquity likely allows them to automatically cherry-pick less "bad code."