As I understand it, user reports go to the community, the community’s instance, as well as the user’s instance if the user is from a separate instance.

My concern is if a user is breaking instance rules across multiple communities it might not rise to a level to catch the attention of instance admins. If my understanding (^) is correct I imagine there is an absolute flood of reports at the instance level making the correlation of reports against a particular user hard to single out.

Is my understanding wrong? Or maybe reports are automatically correlated? Or failing that is there a way to report a user directly to instance admins?