Some units of this lens failed to focus when autofocusing at a closed aperture, or drifted out of focus when the aperture was changed after focusing manually. Sony repaired affected units free of charge under a time-limited programme.
The conditional nature of the fault is instructive: an owner who never stopped down while focusing might have used an affected lens for years without noticing, which is precisely why structured reports capture the circumstances of a failure rather than only its existence.