"Secret Service spokesperson Alexi Worley told Snopes by phone that the white vans were part of the Secret Service's motorcade, "transporting members of the campaign staff and press." As for the people seated inside the restaurant, campaign spokesperson Daniel Wessel told us via email, "I can confirm it was a volunteer appreciation event." Further, a local reporter who was on the scene also provided similar details, which we will go into later in this story."
https://www.snopes.com/news/2024/08/22/harris-restaurant-paid-actors/