Facebook is blocking users from posting some legitimate news articles about the coronavirus in what appears to be a bug in its spam filters, Business Insider reports. 

On Tuesday, multiple Facebook users reported on Twitter that they found themselves unable to post articles from certain news outlets including Business Insider, BuzzFeed, The Atlantic, and the Times of Israel. It's not clear exactly what has gone wrong, and Facebook did not respond to a request for comment.

In the face of the mounting COVID-19 pandemic, Facebook has sent many of its content moderators home, saying it will rely more on automated software instead. Alex Stamos, an outspoken former Facebook security exec, speculated that this shift might be to blame.

"It looks like an anti-spam rule at FB is going haywire," he wrote on Twitter. "Facebook sent home content moderators yesterday, who generally can't [work from home] due to privacy commitments the company has made. We might be seeing the start of the [machine learning going nuts with less human oversight."

Facebook denied that the bug was related to any changes to its content moderator workforce.

On Tuesday Facebook also blocked two news articles of Panorama.am. One of them referred to Russia’s ban on entry of foreign citizens, including Armenian citizens, into the country, while the other had nothing to do with coronavirus. The article was about a BBC documentary on the behavior of Facebook and other social media users.