Thank you for your interest in contributing to CritiqueBrainz!
Our primary Git repository is located at https://github.com/metabrainz/critiquebrainz. That's where all changes should be submitted.
If you want to submit a bug report or suggest an improvement, please use our bug tracker. Try to provide a good description for the ticket. If it's a bug report, tell us how the issue can be reproduced.
All MetaBrainz projects have a set of general contribution guidelines: https://github.com/metabrainz/guidelines. Make sure to take a look at the documents in that repository, especially ones directly related to CritiqueBrainz (Python, SQL, etc.).
One of the best ways to discuss something with us is by connecting to the #metabrainz IRC channel on the Libera.Chat network. Other ways to communicate with us are described at https://metabrainz.org/contact.