The FairPlay certificate rotation theory makes the most sense. Apple has done silent re-signing before when DRM certificates expired. What's unusual here is the

The FairPlay certificate rotation theory makes the most sense. Apple has done silent re-signing before when DRM certificates expired. What's unusual here is the update note surfacing in the App Store UI at all — that's probably an unintended side effect of whatever pipeline they're running this through, not intentional transparency.