It is a bot that these communities on discord can invite to specific channels that will index the discussion to provide a search engine interface. Ideally search engines could leverage the answeroverflow API to help people get access to the technical discussion that now happens in discord instead of forums or mailinglists which do come up in search engine results.
I my experience it generally breaks it. Leveraging cookies on the auth domain is fine, but once you are redirected to another domain, that application needs to take the access and refresh tokens and manage reauthentication as a background process. Simply don’t store those things as cookies though.