On Twitter itself, researchers said the increase in hate speech, antisemitic posts and other troubling content had begun before Mr. Musk loosened the service’s content rules. That suggested that a further surge could be coming, they said.
If that happens, it’s unclear whether Mr. Musk will have policies in place to deal with problematic speech or, even if he does, whether Twitter has the employees to keep up with moderation. Mr. Musk laid off, fired or accepted the resignations of more than half the company’s staff last month, including those who worked to remove harassment, foreign interference and disinformation from the service. Yoel Roth, Twitter’s head of trust of safety, was among those who quit.
The Anti-Defamation League, which files regular reports of antisemitic tweets to Twitter and keeps track of which posts are removed, said the company had gone from taking action on 60 percent of the tweets it reported to only 30 percent.
“We have advised Musk that Twitter should not just keep the policies it has had in place for years, it should dedicate resources to those policies,” said Yael Eisenstat, a vice president at the Anti-Defamation League, who met with Mr. Musk last month. She said he did not appear interested in taking the advice of civil rights groups and other organizations.
“His actions to date show that he is not committed to a transparent process where he incorporates the best practices we have learned from civil society groups,” Ms. Eisenstat said. “Instead he has emboldened racists, homophobes and antisemites.”
The lack of action extends to new accounts affiliated with terror groups and others that Twitter previously banned. In the first 12 days after Mr. Musk assumed control, 450 accounts associated with ISIS were created, up 69 percent from the previous 12 days, according to the Institute for Strategic Dialogue, a think tank that studies online platforms.
Other social media companies are also increasingly concerned about how content is being moderated on Twitter.