When assigning a team with automated review assignment to a pull request, those who belong to that team will be notified by slack even if not assigned as an output.
The only way to turn this off is by disabling the realtime team review notification for individual accounts. However, this setting is useful to be in when I’m a member of a team that does not have automated review assignment turned on.
Resolution: don’t send real time notifications for teams that have automated review assignment turned on. There is also a setting to disable notifications for team with this feature, however this only applies to email notifications not slack notifications.