You can read about the new rating system here since July 2022.
You can check all the ratings and ranks in these pages:
Rating Divisions
Based on your CodeChef overall rating, you will now fall in either Division 1 or Division 2 or Division 3 or Division 4. All CodeChef contests (Long Challenges, Cook-Offs, LunchTimes and Starters) will now have four parallel contests, one for Division 1, one for Division 2, one for Division 3 and another for Division 4. Though a contest could be rated only for some Divisions. You can learn more about this system here.
If you want to know the details about the star system for ratings, you can refer here.
We hope this will help you understand how you are being rated in our contests. However, if you still have any doubts/suggestions, do send them to us at: [email protected] and we will be happy to talk to you.