[rlaabs]

Unfortunately it seems like I was one of "small percentage of Firefox users" this feature is being tested on.

Contrary to what the article claims, there was no way to disable this feature from the menu: it wasn't possible to uncheck the 'Sponsored Top Sites' button.

I had search for 'sponsor' settings in 'about:config' to disable it. Sadly, I don't think most users will be able to figure this out.

I'm seriously reconsidering moving away from Firefox, or at the very least no longer recommending it to non-technical users

[Kinrany]

I had Yandex as a sponsored website when I installed Firefox. The process of removal did seem unnecessarily obfuscated, but I only had to spend like five minutes on it.

[cookie_monsta]

I found the setting by following FF's instructions and turned it off. Took about 5 seconds, I guess a minute total including searching for how to do it.

[thrwn_frthr_awy]

Do you know if your data was shared with advertisers before you were able to turn it off?