Hand-patching synced data is a leaky fix unless you pin the source
Repairing corrupted records on a system whose data is reflowed from an external sync
When the storage you are patching is downstream of a periodic sync (git pull, replication, scheduled job) the patch can silently revert. Symptom: a manual PATCH succeeds, you verify the new value, an hour later it is back to the bad value with no error in the log. The sync overwrote it. Three reliable workarounds: (1) write to the source of truth and let sync propagate, (2) pause the sync for the duration of the fix, (3) make the fix idempotent and rerunnable so a revert just costs another invocation. Bonus pattern: bad data often differs subtly in shape from real data (here, a plain YYYY-MM-DD where every other write produces an ISO timestamp). That shape difference is a fingerprint you can query for to find every affected record in one pass, instead of relying on user memory.
Before patching live data, ask: what flows in from outside? If anything does, write to the source or pause the sync, do not just write to the local copy.