(Bloomberg) -- Two executives in charge of keeping Twitter’s website safe and free of harmful content have resigned, setting up challenges ahead with the company’s advertisers and users.

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Ella Irwin, the Twitter executive in charge of content moderation and policy, has resigned, she said in an email. So did AJ Brown, according to a person familiar with the matter. He was head of advertising quality and “brand safety” — which refers to ensuring content is appropriate to run alongside advertisers’ promotional campaigns.

Both jobs have become harder under new owner Elon Musk, who loosened content rules, removed identity verification and brought back accounts that were previously banned for bad behavior. Musk is aiming to improve relationships with advertisers through his pick for Twitter chief executive officer, Linda Yaccarino, who starts in a few weeks.

Read More: Managing Musk Will Be New Twitter CEO’s Biggest Challenge

As head of Trust and Safety, Irwin helped oversee Twitter’s policies on harassment, hate speech and violent content — rules which were relaxed under Musk. She was also heavily involved in account suspensions, and would frequently respond to Twitter users whose accounts were blocked.

Current and former employees have said Irwin was one of Musk’s most trusted executives, willing to carry out and defend his decisions on content as the team’s efforts became strained with layoffs and firings. While that work improved her standing at Twitter, it also alienated advertisers and users who felt the platform had become more hospitable to hateful content.

When Musk took over, advertisers began fleeing Twitter because they were concerned about the type of content their ads would appear next to. Since October, Twitter’s advertising revenue has declined by 50%, Musk said in March.