Fix the bug, then audit the data for every other instance of the same shape
Recovering from a data-corruption bug where bad attributions accumulated in a database over time before the root cause was identified and patched.
When you ship a fix for a data-corruption bug, the prevention is only half the work. The bad data the bug accumulated before the fix is still there, and it almost certainly affected more than the one record where you noticed it. A self-referential link on one person record turned out to also exist on a second person record — same pattern, different victim. The first cleanup focused on the noticed record and missed the broader audit. The recovery costs more time and creates a worse user experience because every additional discovery is a re-surprise. Treat every data-corruption bug fix as a three-part PR: (1) fix the cause going forward, (2) audit query that enumerates every record matching the bug shape, (3) cleanup operation that handles each result. Skipping step two is how bugs come back two days later from a different angle.
After shipping a fix for a data-corruption bug, write a SELECT that surfaces every other record matching the same shape, run it before declaring the issue done. If it returns more than zero, you have more work the user is about to notice.