Somebody ships a differential privacy layer in front of the event store and leaves the dashboards sitting on top of it. The queries still return, the totals still look like totals, and the ticket gets closed. Nobody on the team computed the floor.
Every private aggregate carries noise, and the noise is unlabeled. It sits in the same cell somebody reads on Monday morning before deciding whether a segment moved, and to the eye it looks like a small real change. In the ad-account work I do, the move to aggregate and private reporting comes from regulation rather than from architecture, so the debate never really happens, and the pattern is always the same: epsilon gets negotiated in a meeting, and the arithmetic that would turn it into a detection limit never makes it into any document.
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