Twitter’s head of trust and safety Ella Irwin resigned from her role at the Elon Musk-owned social media platform.

Irwin, who confirmed her resignation to Reuters on Thursday, served for roughly seven months and declined to provide a reason for her decision.

Irwin ran the Twitter team that fought disinformation, removed offensive content and helped maintain Twitter’s platform integrity. But Twitter has experienced significant challenges in stemming offensive content under Irwin’s tenure and since Musk began serving as CEO.

Musk had previously said, for example, that fighting child sex abuse material, or CSAM, was “Priority #1” for the platform. Reporting from NBC News and CNBC in January found illegal content was still freely circulating on the platform.

Irwin’s departure comes at a turbulent time for the social media network, which was grappling with the dissemination of a conservative website’s purported documentary on transgender people. The video was uploaded to Twitter’s platform Thursday but was “visibility limited,” preventing users from retweeting or commenting on it.

On Friday, Musk shared the video after the visibility restrictions were apparently lifted.

Twitter’s trust and safety team, the unit that Irwin ran until earlier this week, would have had responsibility for limiting the spread of the post. Irwin’s predecessor, Yoel Roth, quit just two weeks into Musk’s ownership.

Musk, who has owned Twitter since October 2022 and has described himself as a champion of free speech, called the tagging a “mistake,” but as of Friday, had not lifted the visibility limitations. The dissemination of explicit, violent or hateful content on social media networks has been of significant concern to lawmakers, regulators, advocacy groups and the public.

Concerns over undesirable content, including racially or sexually offensive material, sparked an advertiser flight shortly after Musk acquired Twitter. He’s taken steps since then to stem the tide and court advertisers, including the hiring of former NBCUniversal ad executive Linda Yaccarino as CEO.

Neither Irwin nor Musk returned a request for comment. Twitter’s press email provided an automated, noninformational response.