Inside Meta Platforms, employees for years have increasingly wondered when Sheryl Sandberg, the longtime chief operating officer in charge of its advertising business and many other functions, would decide to leave. On Wednesday, Sandberg announced she would be out by this fall, ending her 14-year run as the right hand of CEO Mark Zuckerberg and a primary crisis manager and negotiator with politicians, the press and advertisers.

For the Facebook parent company, however, the timing of Sandberg’s departure is far from ideal. Her replacements—namely Javier Olivan, a longtime executive in charge of growing Meta’s apps—must contend with the most difficult period for Facebook since its troubled initial public stock offering more than a decade ago: Its ad business, which generated $115 billion in revenue last year, and app-user growth have slowed considerably. The company is betting big on an uncertain future involving virtual and augmented reality products, some of which it hasn’t released. And numerous senior executives have left in the past year, shrinking Meta’s senior bench.