The message text is still sent to the push notification server from the app's infrastructure - this setting simply stops the phone from displaying the message.

The app itself must choose not to send the message text in the push notification.

Apparently if I’m reading the work of others correctly a notification component and subsequent other interaction logs, in this case that the notification was not generated, is also logged in knowledgeC pointing to at least some metadata of non-notified messages logged.

The signal app does and does the OS once the notification is displayed. The latter is where this issue originates