The extensions are designed to warn users if a URL they are visiting is malicious, phishing, or a scam site.
But earlier this month, Mozilla removed four extensions from the Firefox add-ons site after discovering that they were sending large swaths of user tracking data to Avast.
Avast Online Security, Avast SafePrice, AVG Online Security and AVG SafePrice were caught collecting user behavior data like URLs, deeper browsing history, information about operating systems and other browsing habits.
At the time, Avast said it was working on making changes to the expansions in order to satisfy Mozilla’s requirements.
Although the extensions are now said to be more transparent, researchers are warning that unknown bits of data are still being transmitted.