A swastika. A crossed-out Star of David inside a circle. An image of Black people or Muslims or Asian-Americans captioned “Go back where you came from.” All familiar symbols of hate, all instantly recognizable and all set off social media alarm bells to remove posts and posters alike.

But the haters have learned their lesson and are seasoning their hysteria with nuance and innuendo. The sledgehammer is now tempered and seemingly innocent but vicious messages are eluding the algorithms and making their way with a vengeance on mainstream platforms like Twitter, Instagram, TikTok and Telegram.

Obvious dog whistles such as “white genocide” and “white power” are now passé. The modern extremist greets his or her fellow haters online with a cheery “1488”—the “14” for the 14-word slogan “We must secure the existence of our people and a future for white children”—the “88” for “Heil Hitler,” the letter h being the 8th letter of the alphabet.

A Christian cross emoji in their profile (who can censor that?) or the word “anglo” used strategically in a username are deft ways to avoid detection, as is the innocuous-seeming number “109” representing the lie that Jews have been expelled from 109 countries. Used as a greeting, “109” may be answered with “110” as a jovial reminder that the next country to expel Jews should be our own.

These symbols and others—obvious and subtle—were on display during the January 6th insurrection, indicating the strong presence of far-right extremism on that dark day.

Other codes for hate—and they are plentiful—can be found on the Anti-Defamation League’s hate symbol database. But be warned, these symbols do not thrive in the light, and are swiftly replaced like others, making the job of social media moderators more a game of high-tech Whack-A-Mole.

As David Tessler, the head of dangerous organizations and individuals policy for Meta, said in a statement, “We know these groups are determined to find new ways to try to evade our policies, and that’s why we invest in people and technology and work with outside experts to constantly update and improve our enforcement efforts.”

Mr. Tessler and his colleagues have their work cut out for them as nothing succeeds like success, and as extremist ranks continue to rise there’s no reason to believe the tactics will change anytime soon.

It seems that with every new breakthrough in communication technology we as a species get a chance to show ourselves not just at our best but also at our worst.