It's basically a spyware
https://robertheaton.com/2018/07/02/stylish-browser-extension-steals-your-internet-history/

Steals your browser history.

Violates privacy.

Spyware

Their privacy policy states they collect the following via this extension:

- Standard web server log information (i.e., web request) as well as data sent in response to that request, such as URL used, Internet Protocol address (trimmed and hashed for anonymization), TabID, HTTP referrer, and user agent; and

- Search engine results page data (keyword, order/index of results, links of results, title, description, and ads displayed).

https://userstyles.org/login/policy

THIS ADDON STEALS YOUR INTERNET HISTORY

https://robertheaton.com/2018/07/02/stylish-browser-extension-steals-your-internet-history/

It's basically a spyware
https://robertheaton.com/2018/07/02/stylish-browser-extension-steals-your-internet-history/

Was great in the past, but turned into spying tool! Use forked and clean Stylus!

This addon is a scam. Don't install it.

Privacy nightmare, steals user data, sends all sites visited to SimilarWeb, use stylus instead

Have used this is in the past, but I can't recommend it due to privacy issues. Recording my browsing behavior is not OK.

Abusive extension, collects user history.

This addon has been collecting browser history since January 2017. If you care about your privacy at all you should switch to Stylus instead.

This is nothing but spyware

Spyware

Sends all of your browsing history to a third party server.

Abusive and invasive add-on, which records and tracks all your navigation history.

Records all browsing history. Should be considered insecure, use an alternative.

It's shocking that Stylish steals our browsing history by default.

My visited links are my private information. We might visit web pages that are UNLISTED or not indexed by search engines for private reasons. Or sites we visit might contain sensitive information in the query string, login details, tokens and things we would NEVER want to share with marketing companies.

Collecting this information should be OPT-IN not opt-out. Their claim of "non-identifiable" information is a sham. Browser history can include personal blog pages and other destinations that clearly point to the identity of the user. More than that, the visited pages might be unlisted, unpublished... and why would anyone want those pages sent to a marketing company database? Why would anyone want their browsing history uploaded to a marketing company without being asked first?

That is a below the belt, rotten, scumbag privacy breach.

It's disappointing that browser extensions can do this, and remain on Mozilla's network of addons. This privacy breach should be shut down. Add-ons should NEVER be allowed to collect browser history information by default without first getting permission.