X has seen an increase in problematic content including harassment, disinformation and hate speech since Elon Musk bought the service in 2022. He has loosened the website’s content rules and fired, laid off or accepted the resignations of staff members who worked to remove such content. The platform also reinstated accounts that had been previously banned for violating rules.

Although many of the companies that produce generative A.I. tools ban their users from creating explicit imagery, people find ways to break the rules. “It’s an arms race, and it seems that whenever somebody comes up with a guardrail, someone else figures out how to jailbreak,” Mr. Etzioni said.

The images originated in a channel on the messaging app Telegram that is dedicated to producing such images, according to 404 Media, a technology news site. But the deepfakes garnered broad attention after being posted on X and other social media services, where they spread rapidly.

Some states have restricted pornographic and political deepfakes. But the restrictions have not had a strong impact, and there are no federal regulations of such deepfakes, Mr. Colman said. Platforms have tried to address deepfakes by asking users to report them, but that method has not worked, he added. By the time they are flagged, millions of users have already seen them.

“The toothpaste is already out of the tube,” he said.

Ms. Swift’s publicist, Tree Paine, did not immediately respond to requests for comment late Thursday.

The deepfakes of Ms. Swift prompted renewed calls for action from lawmakers. Representative Joe Morelle, a Democrat from New York who introduced a bill last year that would make sharing such images a federal crime, said on X that the spread of the images was “appalling,” adding: “It’s happening to women everywhere, every day.”