If they are saying this to other employees or other people, this is backbiting. If they are evaluating a certain employee with other managers purely for professional reasons, they can use more diplomatic
language  in order to avoid speaking ill of that employee.

Is it permissible for the owners of a restaurant to talk about the shortcomings and mistakes of their employees. For ex. If they talk about their employees not performing their job, or not using common sense, or not being trustworthy. Is this backbiting? And what are the limits when evaluating employees?