Facebook is testing out a change to their network in six markets. As a result, posts from some publishers and businesses will be removed from the site’s News Feed section. The change has caused a dramatic drop in referral traffic to news outlets.

The posts will now only be shown in a separate tab called ‘Explore Feed,’ which was officially unveiled last week. The test is only active for people in Sri Lanka, Bolivia, Slovakia, Serbia, Guatemala, and Cambodia. Facebook confirmed the test on Monday, which was first spotted by Slovakian journalist Filip Struharik.

Biggest drop in organic reach we’ve ever seen. Pages have 4 times less interactions, reach fell by two-thirds https://t.co/KhAtCR0yvu — Filip Struhárik (@filip_struharik) 21 октября 2017 г.

UPDATE People report several bugs. Some can’t find #ExploreFeed, but page posts already disappeared from newsfeed https://t.co/KhAtCR0yvu — Filip Struhárik (@filip_struharik) 23 октября 2017 г.

Slovak media have 4x less interactions since #Facebook is testing #explorefeed (data by @crowdtangle, 60 biggest FB media pages in Slovakia) pic.twitter.com/UMfEBFz98P — Filip Struhárik (@filip_struharik) 20 октября 2017 г.

Some of the top Facebook pages in Slovakia lost as much as two-thirds to three-fourths of their reach due to the change, according to Facebook-owned analytics tool CrowdTangle.

Stories from publishers and businesses are being transferred from the main feed to the Explore Feed, while the main feed is reserved for posts from friends and family.

It may end up with publishers having to pay Facebook to promote their stories so that people can see them.

Facebook’s News Feed VP Adam Mosseri wrote about the test, saying: “We currently have no plans to roll this test out further.”

Mosseri also tweeted about the length of time the test will take.

Likely months as it can take that long for people to adapt, but we'll be looking to improve the experience in the meantime. — Adam Mosseri (@mosseri) 23 октября 2017 г.

According to Mosseri, “The goal of this test is to understand if people prefer to have separate places for personal and public content. We will hear what people say about the experience to understand if it’s an idea worth pursuing any further… As with all tests we run, we may learn new things that lead to additional tests in the coming months so we can better understand what works best for people and publishers.”

Among others. Most ranking changes are tested for days or weeks, but given how significant a change this is we'll likely run it for months. — Adam Mosseri (@mosseri) October 23, 2017

Facebook has been known to make dramatic changes in their algorithms that affect referral traffic and reach for publishers. Just last year, it changed how the News Feed works, prioritizing posts shared by family and friends over content shared by publishers.