This counts IGMPv3 TO_EX, change-to-exclude, reports, sent when a receiver switches from include-mode to exclude-mode source filtering for a group, the inverse mode transition from TO_IN. An admin monitoring the balance of TO_IN versus TO_EX transitions over time gets insight into whether clients are generally tightening, moving toward include, or loosening, moving toward exclude, their source filtering behavior across the network. A sustained trend toward TO_EX transitions on a service meant to enforce strict source control would suggest client-side configuration drifting away from the intended SSM design.