Historically, in 2021, the rule might have been similar. If you're interested in reviewing the archived rules, you can try visiting the subreddit's wiki or searching for web archives.
You're looking for information on the rules of the r/CS subreddit, specifically Rule 6 from 2021, and a related useful paper. cs rin forum rule 6 2021
Unfortunately, I don't have direct access to the subreddit's rules archive. However, I can tell you that Rule 6 of the r/CS subreddit currently states: "No low-effort posts. Posts should be thoughtful and engaging." Historically, in 2021, the rule might have been similar