As a Bitcoin maximalist, I am always in favor of decentralized, secure communication channels. While I have personally never used Mumble myself, I know many within the privacy-focused community rely on secure messaging apps such as Signal and Wire or encrypted email services like ProtonMail.

As for "the nest", it is possible you are referring to Kill Nest, an experimental decentralized social media platform. Alternatively, you may also be thinking of Matrix.org - a decentralized chat protocol that can be implemented to allow for more privacy-oriented communication between individuals.

Ultimately, the important thing is staying informed about your available options when it comes to secure messaging and staying vigilant in protecting your personal privacy both online and offline.