We have a good dozen of apps utilizing Background notifications. Now as we migrate to the V1 api of Firebase we have a issue in our Android Sending. The issue is, that the device shows the notification even tho there is no ‘notification’ property attached.

All apps work as expected with the old Legacy api(and its legacy payload). So the apps dont seem to be the Issue.

I start to run out of time and ideas.

Here the sent Payload (Values of token and stationId are anonymized):
{ "message": { "token": "---TOKEN---", "data": { "stationId": "---GUID---", "stationName": "INFO", "alarmElement": "ITEM", "tts": "1", "messageType": "1" }, "android": { "priority": "high" } } }

I tried to get information out of the FCM Docs, various SO Articles and even asked some of the popular response generator AI`s