Distrust DarkMatter Intermediate CAs
Mozilla Firefox's root trust store trusts an intermediate ca for a spying firm called DarkMatter. They trust they intermediate ca as it was signed by Quovadis.
This already puts Tor users at risk as they can spy today, however once they are a root ca there will be no oversight by Quovadis/Digicert and they can misbehave and issue secret certificates to spy on Tor users.
They have a business interest in spying on HTTPS traffic. Google Chrome and Mozilla Firefox are still discussing this. It's in the best interest of Tor Users to immediately distrust the intermediate CA.