In October, one day after Facebook announced that it would ban Holocaust denial, Izabella Tabarovsky received an unexpected message from the platform.

A 2019 post of hers promoting an article she had written on Holocaust remembrance was being removed for violating Facebook’s “Community Standards on hate speech.” No further information was provided, and Tabarovsky doesn’t recall being given a way to appeal the decision.

She reached out to a Facebook spokesperson she found on Twitter but got no response.

Facebook’s decision to ban Holocaust denial came only after scholars, activists and celebrities had pilloried the platform for allowing hate speech. But Tabarovsky is no Holocaust denier. She’s a Jewish journalist who writes about Soviet Jewry, including the Holocaust in Soviet territories.

The article in question was called “Most Jews Weren’t Murdered In Death Camps. It’s Time To Talk About The Other Holocaust.” It was about how efforts at Holocaust remembrance don’t focus enough on the millions of Jews who were killed outside the concentration camps, such as Tabarovsky’s own relatives, who were murdered at Babyn Yar.

It’s possible the headline tripped up an algorithm meant to detect Holocaust denial, which then blocked Tabarovsky’s post. She doesn’t know, as she never heard from Facebook.

“This message popped up, and obviously the first reaction is, what did I say that was hateful?” Tabarovsky told the Jewish Telegraphic Agency. “We’ve seen so much antisemitic speech. They can’t battle it, they can’t take it down, and yet they remove Holocaust education posts from 2019. It’s truly incredible.”

Tabarovsky is among the long list of social media users whose anti-hate posts have mistakenly fallen victim to the algorithms that aim to remove hate speech. Companies such as Facebook, Twitter and TikTok say they have stepped up their fight against abusive posts and disinformation. But the artificial intelligence that drives those systems, intending to root out racism or calls for genocide, can instead ensnare the efforts to combat them.

Organizations that focus on Holocaust education say the problem is especially acute for them because it comes at a time when large percentages of young people are ignorant of basic facts about the Holocaust, and more online than ever.