Wapo did an article on this based on info from below, it’s lackluster in comparision but I did include link and pauywall workaround below. Otherwise, my apologies if you just ate (turns my stomach anyways) 
DataSpii: The catastrophic data leak via browser extensions
Sam Jadali
SecurityWithSam.comAbstract
We present DataSpii (pronounced data-spy), the catastrophic data leak that occurs when any one of eight browser extensions collects browsing activity data — including personally identifiable information (PII) and corporate information (CI) — from unwitting Chrome and Firefox users. Our investigation uncovered an online service selling the collected browsing activity data to its subscription members in near real-time. In this report, we delineate the sensitive data source types relevant to the security of individuals and businesses across the globe. We observed two extensions employing dilatory tactics — an effective maneuver for eluding detection — to collect the data.
We identified the collection of sensitive data from the internal network environments of Fortune 500 companies. Several Fortune 500 companies provided an additional measure of confirmation through a process of responsible disclosure. By deploying a honeypot to monitor web traffic, we discovered near-immediate visits to URLs collected by the extensions. To address the evolving threat to data security, we propose preemptive measures such as limiting access to shareable links, and removing PII and CI from metadata.
Imagine if someone could publicly access, in near real-time — within an hour — your sensitive personal data on the websites you are browsing. Imagine, further, this person could access your sensitive business data in much the same way. Moreover, what if you and/or your colleagues were, yourselves, unwittingly leaking such data? In Table 1 below, we enumerate the types of data that can be accessed.
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for wapo article to workaround their paywall, use DDG to search for the full article title,
eg. https://duckduckgo.com/html?q=I%20found%20your%20data%2C%20it's%20for%20sale.
original article should popup in top 1-3 results, open from there (and if safest setting on Tor, please do temp allow script permissions to fully load, select free and re-alllow script permissions when page resolve with block complaining about private mode… anyway, be sure clean up after, wapo is a cesspool of trackers. direct link:
https://www.washingtonpost.com/technology/2019/07/18/i-found-your-data-its-sale/