The problem: every offline feature on my map app is built on a map that was also talking to the internet ten seconds ago. That's the moral hazard of offline development — flipping airplane mode and saying "looks fine" hides bugs where dynamically-fetched tiles are silently stitched in alongside the deliberately-cached ones. The current "Offline" basemap option suffers exactly this: it's the same Mapbox instance that loads vector road labels, satellite imagery, and Esri layers from the internet the rest of the time.