Cover image source: RDNE Stock project by RDNE If you've been building Flutter apps for a while, you know the sinking feeling of a QA report saying: "Push notifications stopped working on iOS." You check the code, and nothing has changed. You check Android, and it works perfectly. Then you log into Firebase and see it: The dreaded red box. Your APNs certificates have expired. In this article, we'll dive into the fundamental difference between APNs Certificates and Auth Keys, and why as a seasoned developer, you should almost always choose the latter. The Contenders: .p12 vs. .p8 For years, developers relied on APNs Certificates (.p12 files) . While they work, they come with a high maintenance cost. Recently, Apple introduced APNs Authentication Keys (.p8 files) , which have quickly become the industry standard. 1. APNs Certificates (.p12) Expiration: They expire every 12 months . If you forget to renew them, your production notifications stop instantly. Scope: Each certificate is tied to a single App ID .…