There are several ways you can report bugs or create enhancement requests. First, you can reach out to our technical support team who can help you create an issue, or point you to an already existing issue.
TeamCity also operates a public issue tracker where you can create, commend, vote, and follow bugs and enhancement requests.
For functionality related to the core TeamCity product, you can open requests at https://youtrack.jetbrains.com/issues/TW
For issues specifically related to TeamCity Cloud, please use https://youtrack.jetbrains.com/issues/TCC