If there is a problem with the latest release of esoBB, the best course of action is to create an issue if there isn’t one already, or start a new conversation on the support forum. Downgrading to an older version of the forum software rarely solves anything and is only useful in the development context. If you run a production forum, you should maintain the latest version of the software or risk exposing your users to potential security vulnerabilities.
On the other hand, if you aren’t running a production forum and only wish to test older versions for development purposes then they are available on this page, including older versions of esoTalk.