Grok 4 is xAI’s most advanced model yet, but early praise is clashing with old scandals and fresh tests of its limits.

On Wednesday night, Elon Musk unveiled xAI's latest flagship models Grok 4 and Grok 4 Heavy via livestream, just one day after the company's Grok chatbot began generating outputs that featured blatantly antisemitic tropes in responses to users on X.

A few weeks ago, while comparing language proficiency in essays written by ChatGPT with that in essays by human authors, I had an aha! moment. I realized that I was comparing a single voice—that of the large language model,