Yes, but Matrix a plague of questionable open-source and a metadata disaster.
Matrix’s E2EE does not, however, encrypt everything. The following information is not encrypted: Message senders, Session/device IDs, Message timestamps, Room members (join/leave/invite events), Message edit events, Message reactions, Read receipts, Nicknames, Profile pictures
Matrix is developed by a for profit entity, a group of venture capitalists and having a spec doesn’t mean everything. The way Matrix is designed is to force people into jumping through hoops and kind of drawing all attention to Matrix itself instead of the end result.
Decentralized communication protocol Matrix shifts to less-permissive AGPL open source license Element, the company and core developer behind the decentralized communication protocol known as Matrix, has announced a notable license change that will make the open source project just that little bit less appealing for companies looking to build on top of it.
Stop recommending questionable open-source like Matrix. XMPP is the true and the OG federated and truly open solution that is very extensible. XMPP is tested, reliable, secure and above all a truly open standard and decentralized it just lacks some investment in better mobile clients.
What people fail to see is that XMPP is the only solution that treats messaging and video like email: just provide an address and the servers and clients will cooperate with each other in order to maintain a conversation and it can be configured to be secure and private. Everything else is just an attempt at yet another vendor lock-in. Here a quick overview of the architecture.