While Facebook continues to struggle with Holocaust denial on its platform, policies implemented by YouTube and Reddit show that eliminating anti-Semitism on social media is still possible, a British think tank claimed in a report released last week.

The document, from the Institute for Strategic Dialogue, tracked the frequency of the word “Holohoax” - a common term for Holocaust deniers - on various social media platforms over the past two years. It found that Facebook, the world’s largest social media network, “provide[s] a home to an established and active community of Holocaust deniers,” whereas such conspiracy theories had significantly decreased on YouTube after a policy change by the Google-run company in 2019.

The report found 36 Facebook groups specifically dedicated to Holocaust denial, and argued that the platform’s algorithm created a “snowball” effect whereby people who like one piece of anti-Semitic content will be recommended similar pages.

Facebook has been criticized for years for its laissez-faire approach to Holocaust denial. CEO Mark Zuckerberg said in a 2018 interview that he was opposed on principle to removing many forms of hate speech from the social network. “I’m Jewish, and there’s a set of people who deny that the Holocaust happened. I find that deeply offensive,” he told Recode’s Kara Swisher. “But at the end of the day, I don’t believe that our platform should take that down because I think there are things that different people get wrong.”

That stance has been criticized by several civil rights organizations. Among those has been the the Anti-Defamation League, which is among the leaders of a campaign to boycott Facebook until it changes its practices. “Holocaust Denial is a despicable, antisemitic conspiracy theory that Jews hoaxed the entire world and @ISDglobal’s research reinforces what we know to be true: Facebook not only profits off hate, they amplify and recommend it,” he wrote on Twitter.