Correct me if I am wrong: If you use steam console to download an old version of the game, regardless of currently installed version, steam downloads the whole game. Let’s say I was on v2.1, the game received an update v2.2 and I downloaded it normally through Steam, this downloads only the difference between 2.1 and 2.2. Let’s say I have 2.2, the game doesn’t use the “betas” feature and I want to downgrade the game. Steam ignores the current 2.2 install and downloads 2.1 in its entirety.