Specialists from PrivacyGuides have removed Session and Element/Matrix from the list of recommended messengers The Best Private Instant Messengers - Privacy Guides. The main reason for the removal is the lack of forward secrecy:
These messengers do not have forward secrecy, and while they fulfill certain needs that our previous recommendations may not, we do not recommend them for long-term or sensitive communications. Any key compromise among message recipients would affect the confidentiality of all past communications.
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ps @Patrick, I will mention the problem of forward secrecy in the Matrix and Element sections and add a links in wiki Instant Messenger Chat. And I will remove the duplicate mention of CVE in the Matrix section.