good extension but I had conflicts issues with Mullvad VPN check status site if I use it in combination with the "disable webRTC" add-on:

https://am.i.mullvad.net/

it lost time for Checking for WebRTC leaks and then it shown "Failed checking for WebRTC leaks."

https://mullvad.net/en/guides/webrtc/

https://addons.mozilla.org/en-US/firefox/addon/happy-bonobo-disable-webrtc/