True or not?
No, WhatsApp did not.
Messages are not exposed to the operator. If you exploited this vulnerability, you could not read messages that had already been sent.
Instead, what happens is, everyone is notified of a new arrival, and then can decide whether or not to keep communicating through that channel.
That is NOT the same thing as "leave messages exposed to the operator" in any stretch of the imagination.
True or not?