In some special cases, push notifications are shown after the device comes online

[meafs]

If a device is offline, fcm messages are received when the device gets online (ie. Connects to the internet). Usually fcm by default gets stored for 4 weeks ( Something like ttl on domains) & as I have said on issue: sustcast/sustcast-core-v0#40

For custom programs that are aired at a specific time , a notification saying "We're live blah blah blah" at a later time may lead to misunderstanding about the fact that, the program is being aired then. In reality it's not. It's fcm that triggers the notification at a later time.