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US Feds Are Tapping a Half-Billion Encrypted Messaging Goldmine
(www.404media.co)
This is a most excellent place for technology news and articles.
I don't think that's how it works? It's the client application that has the key for the end to end encryption, not the server. I don't think you need to trust the matrix server you use? I could be wrong, I don't know matrix particularly well.
https://www.wired.com/story/matrix-patches-vulnerabilities-that-completely-subvert-e2ee-guarantees/