There have been several occurrences recently of people bringing issues from other wikis to this one. So far the people doing so have violated other rules, and have been blocked for those violations. I can provide links if people want, but I'd rather not call attention to them by linking, and the most recent incident included content which was so offensive that it's been removed.
Because of incidents, I'd like to add a Severe level rule against bringing issues from other wikis to this one. At that level, someone could be blocked for 3 months the first time they do so.
I emphasize "could", because the CoC encourages admins to take less than the maximum allowed action, and if someone were to be polite with the cross-wiki issues, my preferred course of action would be to politely ask them to stop.