At this time, Mixpanel’s Android push services leverage Google Cloud Messaging (GCM) instead of Firebase Cloud Messaging (FCM). Mixpanel plans to transition push infrastructure to FCM as Google has deprecated GCM and fully adopted FCM.
Mixpanel supports FCM for new implementations, as well as GCM for existing implementations. To use FCM, pass your FCM Sender/App ID into the initPushHandling function, and use your Firebase API Key for delivery.
Moving from GCM to FCM
Your users’ existing push tokens will work with your updated FCM API key if moving from GCM to FCM.