Not every change is going to completely overhaul the app. More than likely, the changes are a fix to some obscure bug not caught in testing that only affects a small percentage of devices. Just because you don’t encounter it with your workflow and device doesn’t mean it isn’t a critical bug preventing someone from using the app. It could also be a new feature targeting a different use case to yours. It could even be as simple as bringing the app into compliance with new platform requirements or government regulations (which can happen a couple times a year, for example Android often bumps the minimum SDK target such that apps are forced to comply with new privacy improvements).