These points are good to know, but as others pointed out they apply to email, Matrix, ActivityPub and other federated protocols. I believe we have published a rather comprehensive security/privacy FAQ here: https://joinjabber.org/faqs/security/

Let me know if you find some information missing in there!

PS: I don't understand why the infosec-handbook.eu article appears posted on november 1 2021. It was published in August 2018, see also: https://web.archive.org/web/20201208132104/https://infosec-h...