Expense management startup Brex, which was valued at $12.3 billion two years ago, laid off 282 people, or about 20% of its staff today. The once high-flying fintech startup sent a note to employees (that was also published on the company’s website) today, announcing the news. In addition, Brex announced that its COO, Michael Tannenbaum, is transitioning from his role to become a board member.