What topics can I ask about here?
Please limit your questions to specific queries about members of the Vi and Vim family of editors. See this meta question about What is considered to be vi?
Questions about Vim plugins are on topic but be aware that bug reports and feature requests for a plugin would be better off in that plugin's issue tracker. Most of the plugins available on Github use the built-in issue tracker. (The "Issues" tab in the top menu.)
Questions about plugins that replicate Vim's editing model in other editors (VSCode, Sublime Text, Emacs, etc.) may be on topic if they are about features or behavior that also exists in Vi or its derivatives, as discussed in the meta question linked to, above.
While pure VimGolf questions are not on topic here, questions about how to do something more efficiently or how to improve your workflow in Vim are allowed as long as they are not too broad.
If your question is not specifically on-topic for Vi and Vim Stack Exchange, it may be on topic for another Stack Exchange site. If no site currently exists that will accept your question, you may commit to or propose a new site at Area 51, the place where new Stack Exchange communities are democratically created.