I don't want to defend Discord, but that's just not true. That announcement did not say all processing would be on-device, only when you use the face scan.
> Video selfies for facial age estimation never leave a user’s device
> Facial scans never leave your device. Discord and our vendor partners never receive it.
Meanwhile they're also clear that uploaded IDs do get sent to "partners":
> Quick deletion: Identity documents submitted to our vendor partners are deleted quickly— in most cases, immediately after age confirmation.
Ah, I assumed that Persona is being used for face scans too. I haven't been able to find a screenshot of the actual flow, but based on this article [1] with a screenshot of the message UK users are receiving, I suspect they are:
>The information you submit will be temporarily stored for up to 7 days, then deleted. For ID document verification, all details are blurred except your photo and date of birth... [emphasis mine]
To me, that implies that Persona is/was doing more than just IDs.
> Video selfies for facial age estimation never leave a user’s device
> Facial scans never leave your device. Discord and our vendor partners never receive it.
Meanwhile they're also clear that uploaded IDs do get sent to "partners":
> Quick deletion: Identity documents submitted to our vendor partners are deleted quickly— in most cases, immediately after age confirmation.