https://www.steamgifts.com/discussion/eIkkz/are-these-overpriced-games-being-created-to-farm-cv-on-sg-update-all-games-now-give-0-cv

Because games that are designed/bought to abuse cv like this, is not gonna be allowed, they can be retroactively be put to no CV and you will drop back your level.

Because you know fully well these games you bought have been cheap and it's unfair to those that buy real expensive games like Call of Duty: Modern Warfare 2, that's why it happens like it does.