TwitEmbed от Vi Georgeson

Extension that replaces sharing links through the "Copy Link" Button on Twitter with "Copy Embed", which links to the user's chosen redirect domain, (fxtwitter, vxtwitter, fixupx, etc.) improving ease-of-use while sharing on platforms such as Discord. Also includes a hotkey (ctrl+c) to embed while focused on a tweet.

This extension is a fork of the "vx-twitter" extension found here: https://addons.mozilla.org/en-GB/firefox/addon/vx-twitter/
This was done due to recent changes in Twitter's structure causing that add-on to cease functionality.