I'm aware of "Find My Device" that's a documented feature. Find My beacons go OUT
(your device tells others where it is). This is 84MB coming IN. Different thing.
84.5 MB through utun2/IDS during stated isolation—benign or not—contradicts "wireless features turned off" and users have no verification path.
The "closed source" problem you identified is the core issue. So to be rigorous, plausible deniability ends where the telemetry contradicts the UI.