I have an Android application that has notifications with Firebase, and most clients receive notifications, but a few do not. I have tried using their credentials and I receive notifications correctly. I do not understand why some receive notifications well and others do not.
Can someone help me understand it?
This is very tricky subject. Mostly on Android devices. My experiences was mixed up with this topic. Usually android users do not get notifications because of complex Android OS set, where you can block/unblock certain types of notifications (in app, or background, or killed app states). You can even sometimes block notification events if device is locked. It would be good if you could actually get one of devices that do not get notification, and debug on whats going on.
We need to get more informations about this, so we could help you in any way. I think the number one thing would be to check with users if they get notifications from other apps, if they have changed default configuration for push notifications, and lastly to get in hand of one device that has issues.
I hope you will get some information soon to share on this