Version the comparison profile with a hash version column, since changing tracked fields or normalization makes every record look updated. Without raw payloads, do one silent baseline run and flag those change rows so alerting skips them. Keep retry idempotency on change id plus subscriber id, so repeat updates still notify

Run light checks like null rates on every run, and save the heavy ones for when something looks off. Scope quarantine to the source or run, and don't let missing runs tick up during it or you'll fake removed events