Sygnal sends all pushes with high priority level (apns-priority 10 for iOs, and high for android), even for low priority events.

Priority of FCM push are explained here: https://firebase.google.com/docs/cloud-messaging/concept-options#setting-the-priority-of-a-message

This make the device to wake up, and the app to wake up and perform a sync.

On big accounts, it can be more than every 30 seconds, which make the Gplay app syncs more than the F-Droid version, which syncs every 30 seconds, when the app is in the background

In Android P, the system may ignore high priority Push for applications which are abusing high priority push (see https://developer.android.com/topic/performance/power/power-details)

The Android system may consider that the application is too battery greedy and will display some warning which is a bit annoying and deceptive for the user (along with the fact that the battery of its device is drained fast) (screenshot in French):

So we should use high priority Push for noisy event, and for event in e2e rooms maybe, and else use normal priority Push, which let the system choose when to deliver the Push to the app, regarding the current power mode of the device (screen on, idle, idle screen off not moving, etc.).

To fix that, Sygnal should know is the push to send has to be high or low priority, which may lead to change in the API.

Related issue:

• RiotX consumes huge amounts of battery element-hq/element-android#536