As evidence, the lawsuit cites unnamed “courageous whistleblowers” who allege that WhatsApp and Meta employees can request to view a user’s messages through a simple process, thus bypassing the app’s end-to-end encryption. “A worker need only send a ‘task’ (i.e., request via Meta’s internal system) to a Meta engineer with an explanation that they need access to WhatsApp messages for their job,” the lawsuit claims. “The Meta engineering team will then grant access – often without any scrutiny at all – and the worker’s workstation will then have a new window or widget available that can pull up any WhatsApp user’s messages based on the user’s User ID number, which is unique to a user but identical across all Meta products.”
“Once the Meta worker has this access, they can read users’ messages by opening the widget; no separate decryption step is required,” the 51-page complaint adds. “The WhatsApp messages appear in widgets commingled with widgets containing messages from unencrypted sources. Messages appear almost as soon as they are communicated – essentially, in real-time. Moreover, access is unlimited in temporal scope, with Meta workers able to access messages from the time users first activated their accounts, including those messages users believe they have deleted.” The lawsuit does not provide any technical details to back up the rather sensational claims.
The centralized server is only important because it sends you the message to get around the encryption (either adding a new client to your list of trusted clients or in some other way getting your client to send your messages to Meta).
Because the client is capable of adding the backdoor, it isn’t comprosing the encryption. When you add a desktop client to your Signal account it doesn’t break E2E encryption either but your messages are visible in more places. That (or something like it) is what is being described, Meta aren’t decrypting your messages as they go through their E2E network, they are tapping them client side.