Google’s top search executive said concerns about Amazon.com Inc. keep him awake at night as the company loses users to the online retail giant and newer apps such as ByteDance Ltd.’s TikTok.

Testifying as part of the Justice Department’s antitrust case against Google Thursday, Prabhakar Raghavan, a Google senior vice president, said young people in particular are using apps such as TikTok and Meta Platforms Inc.’s Instagram and WhatsApp, where they spend an average of four hours per day.