Even if you’re using a privacy-focused app like Signal, if your messages are shown in notifications (which is the default), Apple will give up your messages with a subpoena. You can turn off showing the message contents in notifications, which you’ll need to do and then convince all your friends to do as well if you want messages to be truly private

Is this true? I.e. Apple can ship notification contents after an app has made the actual notifications with contents? Can’t read the linked article behind the paywall