What do you think about the "issues" Winfred Tilanus is explaining here:
https://media.ccc.de/v/oscal19-12-the_hairy_issue_of_end_to_end_encrypted_instant_messaging
*IM*
Here is written version:
https://blog.apnic.net/2020/03/19/the-hairy-issue-of-end-to-end-encrypted-instant-messaging