Got the same issue, when I clicked on the message, it took me to a thread saying there was a group name change for a group I am in.
Video of me clicking on the notification:
https://gyazo.com/e64b3def249bfdbd040808785927a57e
It appears I am only getting this notification for group name changes, not for user messages.
Outputs;
Was getting this error before the outage (displayed in the video attached)
Private messages API returned status 200 on the conversation ID,
