Every time someone mentions XMPP I want to link this Soatok’s blogpost.

Against XMPP+OMEMO

uMatrix

• No longer maintained, the last release was Sept 2019 except for a one-off patch to fix a vulnerability.
• Everything uMatrix did can be covered by prefs or other extensions: use uBlock Origin for any content blocking.

https://github.com/arkenfox/user.js/wiki/4.1-Extensions#-dont-bother