> TL;DR: As the client applications of WhatsApp are closed-source, claims of end-to-end encryption cannot be validated

For end-to-end encryption to be of any value, you must trust also the OS and the service provider (Meta, Signal, etc) that it doesn't "telemetry" your key.

Good luck

Every encryption is end to end if you're not picky about the ends.

Who would trust facebook ? Excuse me, "Meta"

All this article is about is complaining about Whatsapp not being open source therefore not verifiable. But a symptom from Whatsapp shift to the alleged E2E has been that media sent in groupchats disappears permanently after a while if no one stores it.

I wouldn't use Whatsapp for secure communication anyways, so I much rather prefer they store all the contents on their servers so they are always available than having to loose content in groupchats over the years.