I'm not in the least surprised. Think of other popular messaging systems that claim to offer some kind of E2EE, but are proprietary software: WhatsApp, Skype,

I'm not in the least surprised. Think of other popular messaging systems that claim to offer some kind of E2EE, but are proprietary software: WhatsApp, Skype, FB Messenger, Viber, Threema, Line… Distrust by default! I am always amazed when folks even consider the alleged support for strong E2E encryption in those apps… the value of those claims is exactly zero.