How to add buttons in ionic FCM push notification

I would like to send a push notification with 2 buttons: subscribe and unsubscribe.
I am receiving the notification, but it does not have the buttons.
here is the code of the notification:

let notification = {
      "notification": {
        "title": title,
        "body": msg,
        "sound": "default",
        "click_action": "FCM_PLUGIN_ACTIVITY",
      "actions": [
            "title": "Subscribe",
            "action": "subscribe",
            "title": "Unsubscribe",
            "action": "unsubscribe"
      "priority": "high"

Help me please

@rapropos please can you help me?