The content of the message is E2EE except when it is not with the loophole you mentioned. The major difference between Whatsapp and Signal is the metadata colle

The content of the message is E2EE except when it is not with the loophole you mentioned. The major difference between Whatsapp and Signal is the metadata collection. Meta can record each message sender, receiver, time, size of message, length, device ID in some cases, location and more. This is valuable information for the authorities. Signal encrypts metadata and knows the first time a number connected to the service and last time they connected and have consistently only been able to provide that when given a warrant.