Undocumented push notification error from FCM - DeveloperError

Please provide the following:

  1. SDK Version: 37
  2. Platforms(Android/iOS/web/all): Android and iOS

Sometimes I notice i get this push ticket error (when sending with expo.sendPushNotificationsAsync):

{
  "id": "2b9b09d8-44e2-45d5-b8f8-3147382efe1f",
  "status": "error",
  "message": "The request sent to the server was malformed or contained invalid parameters.",
  "details": {
      "error": "DeveloperError",
      "fault": "developer",
      "fcm": {
          "httpStatus": 404,
          "response": "<HTML>\n<HEAD>\n<TITLE>Not Found</TITLE>\n</HEAD>\n<BODY BGCOLOR=\"#FFFFFF\" TEXT=\"#000000\">\n<H1>Not Found</H1>\n<H2>Error 404</H2>\n</BODY>\n</HTML>\n"
      }
  }
}

The message payload sent was:

{
  "to": "ExponentPushToken[REDACTED_REDACTED_REDACTED]",
  "sound": "default",
  "title": "Masjid Al-Shareef Of Long Beach - New Event",
  "body": "Now hosting \"Junnah June 19 2020\" - 1:00 pm.",
  "_displayInForeground": true,
  "priority": "high",
  "channelId": "updates",
  "data": {
      "partialMasjid": {
          "id": 4,
          "name": "Masjid Al-Shareef Of Long Beach"
      }
  }
}

The only documented error on send is DeviceNotRegistered - https://docs.expo.io/guides/push-notifications/?redirected#push-ticket-errors

Does anyone know what this DeveloperError can mean?