After listeria was discovered at the LAX facility of caterer Gate Gourmet, American Airlines (and later others) stopped using them to provision food for flights.
That’s a smart precaution to take, but it created big operational problems. It’s meant double catering some flights into Los Angeles so there’d be food and beverages for flights out of LA. It’s meant providing food for passengers to bring onboard. And they’ve been transitioning to other caterers as much as possible to bring back meal services for flights.