So you were controlling characters in another client window without that window being your active client at the time?
We are not permitted to do anything that would streamline playing. That means you are unable to do anything at all that would allow you to control characters outside of your current active client.
Blizzard post about policy update on multiboxing rules: https://us.forums.blizzard.com/en/wow/t/policy-update-for-input-broadcasting-may-2021/956613