Work out what this report actually measures

Inheriting a dashboard whose numbers nobody can explain.

Reverse-engineer what this report really measures, as opposed to what it is labelled.

From the query and definitions below:
1. State the true population after every filter and join is applied. Name each group that is silently excluded.
2. State the true grain and the true time basis, including which timestamp actually drives the period.
3. Compare that to what the metric name and the chart label imply. List every gap between the two.
4. Identify hardcoded values, magic numbers, and one-off exclusions, and guess what incident each was added for.
5. Say under what conditions this number moves for reasons unrelated to the thing it claims to track.

Finish with a plain-language sentence a stakeholder could read: this chart shows X for Y, excluding Z.

Query or report definition:
How it is labelled:

Numbers and metrics. Pinning down what a metric means, what a report measures, and whether a surprising number is real.