One of the world’s largest advertising groups is recommending its clients put a pause on deals with Twitter as the social media company undergoes tumultuous changes, the Verge reports. Omnicom, which represents mega-corps like Apple, Pepsi, and McDonalds, sent a memo advising against partnerships with Twitter, citing “continued brand safety concerns” like verified imposter accounts and the recent departure of Twitter’s trust and safety teams. “Evidence that the risk to our clients’ brand safety has risen sharply to a level most would find unacceptable,” the internal document reads. The memo stated that Omnicom had asked Twitter for assurances that the platform is safe for advertisers but “seemingly due to the lack of senior leadership now in these areas, Twitter has not been able to give those assurances.” The move follows other major advertising pauses since Elon Musk took over the company two weeks ago. Advertising agency IPG issued a similar recommendation for its clients last week and large companies like General Motors have also yanked their ad buys from Twitter.