Twitter's head of trust and safety, Ella Irwin, told Reuters on Thursday that she has resigned from the social media company, which has faced criticism for lax protections against harmful content since billionaire Elon Musk acquired it in October.

Irwin, who joined Twitter in June 2022, took over as head of the trust and safety team in November when previous head Yoel Roth resigned. She oversaw content moderation.

An email to Twitter returned an automated reply with a poop emoji. Irwin declined further comment and Musk did not immediately respond to a request for comment.

Irwin's departure comes as the platform has struggled to retain advertisers, with brands wary of appearing next to unsuitable content.

Musk announced earlier this month that he hired Linda Yaccarino, former NBCUniversal advertising chief, to become Twitter's new CEO.

Fortune earlier reported that Irwin's internal Slack account appeared to have been deactivated.

Since Musk's acquisition, Twitter has cut costs dramatically and laid off thousands of employees, including many who had worked on efforts to prevent harmful and illegal content, protect election integrity, and surface accurate information on the site.

Musk has promoted a feature called Community Notes, which lets users add context to tweets, as a way to combat misleading information on Twitter.

The company is also facing increasing scrutiny from regulators over its moderation efforts. Twitter withdrew from a voluntary agreement with the European Union to tackle disinformation, while saying it was committed to complying with upcoming internet rules in the EU.

EU industry chief Thierry Breton warned Twitter last week that it would not be able to avoid legal obligations in the EU after quitting the voluntary agreement.