The privacy concerns you’ve linked are 4 years old, and were questionable at the time, and thoroughly outdated by now. We addressed the more valid criticisms in

The privacy concerns you’ve linked are 4 years old, and were questionable at the time, and thoroughly outdated by now. We addressed the more valid criticisms in Sept 2019: https://matrix.org/blog/2019/09/27/privacy-improvements-in-synapse-1-4-and-riot-1-4 https://matrix.org/blog/2019/09/27/privacy-improvements-in-s.... So, don’t believe everything you read on the internet. The sibling comment is right in saying that Matrix’s encryption still has rough edges though, and we are chipping away at that constantly (eg just rewrote the crypto on Element iOS in Rust; about to launch the same on Android; Web/Desktop next month; etc - so at least we only have one codebase to find the remaining bugs).