Ref T13164. See PHI765. We currently show "Rejected: Herald" in the push log UI, but don't show which rule rejected a push.
We store this data, and it's potentially useful: either for hunting down a particular issue, or for getting a general sense of how often a reject rule is triggering (maybe because you want to tune how aggressive it is).
Show this data in the web UI, and include it in the data export payload.
