iOS: Can't process background notification on low battery

[KorzeniewskiGrzegorz]

Expected Behaviour

In iOS,background notifications should be processed every time, regardless the low battery (<20%).

Actual Behaviour

On iOS, i am able to process notification in background ONLY if the battery percentage is greater than 20% . If it's less , i only receive the notification, but it is not processed in background (doesn't matter if the device is being charged or not).

Steps to Reproduce

1. Battery percentage less than 20% ( doesn't matter if the device is being charged or not).
2. Send notification to the device with content_available set to true (FCM legacy API).
3. See if notification is processed in background.
4. Charge battery more than 20%.
5. Send notification.
6. The device should process the notification in background.

Platform and Version

iOS 13.5.1

Cordova CLI version and cordova platform version

cordova --version              9.0.0
cordova platform version ios   5.1.1
xcode                          11.3

Plugin version

 phonegap-plugin-push  2.3.0

Sample Push Data Payload

I am using legacy FCM API :

{
"registration_ids":"aValidToken",
"notification":{
    "body":"Some body",
    "title":"Some Title",
    "vibrate":1,
    "sound":"default",
    },
 "content_available":true,
 "data":{
      "tipomensaje":"mensajesimple",
     },
 "priority":"high",
}

Sample Code that illustrates the problem

code that I use to process notification:

` push = PushNotification.init({
            android: {},
          browser: {
            pushServiceURL: 'http://push.api.phonegap.com/v1/push'
          },
          ios: {
            alert: 'true',
            badge: 'true',
            sound: 'true'
          },
          windows: {}
        });
        push.on('registration', function(data) {
            localStorage.setItem('regId', data.registrationId);
            $('#regId').val(data.registrationId);
        });
        push.on('error', function(e) {
            debug("push error = " + e.message);
        });

        push.on('notification', function(data) {
            push.getApplicationIconBadgeNumber(function(count) {
                debug('get badge : ' + count);
                count++;

                push.setApplicationIconBadgeNumber(function() {
                    debug('set badge : ' + count);
                }, function() {
                    debug('set badge error');
                }, count);

            }, function() {
               debug('get badge error: ' + count);
            });

            var configuracion = data.additionalData;

            if(configuracion.foreground){
                $('#centro_mensajes').css('display','block');
                $('#aviso_mensaje').text(data.title +"\n"+data.message);
                actualizaruids();
            }

            msg_id = data.additionalData['gcm.message_id'];
             push.finish(
            () => {
                debug('processing of push data is finished for ID=' +  msg_id);
            },
            () => {
                debug('something went wrong with push.finish for ID =' +  msg_id);
            },
           msg_id
        );
        });

Logs taken while reproducing problem

none