Centralized proprietary software on on proprietary platforms can always be opted into a special update that makes all the private keys deterministic making end to end encryption useless for anyone with knowledge of that targeted backdoor.
Only FOSS can deliver verifiable E2EE, and all centralized and proprietary solutions like Zoom, Whatsapp, Instagram, etc should end the security theater.
I applaud Meta for at least being honest about one product.
Centralized FOSS software can do the same thing and remove encryption. Open source is not a requirement for security.