Push Notifications are not working properly on specific Android phones.
I use the word ‘ properly ’ because users receive push notifications when the app is open but not when it is closed, which defeats the purpose of push notifications.
I use the words ‘ specific Android phones ’ because this issue is noticed only on phones by manufacturers like Xiaomi, Oppo, One Plus, Vivo, Lenovo, Huawei, Vivo, Samsung, and a few others.
https://medium.freecodecamp.org/why-your-push-notifications-never-see-the-light-of-day-3fa297520793
这下面一堆用国产手机出问题的人
https://github.com/firebase/quickstart-android/issues/41