An employee is obligated to be loyal to their employer. The higher the position, i.e. the more responsibility and the higher the position, an employee has, the greater the demand for loyalty that the employer can make on the employee.
Disloyal behavior includes, among other things, engaging in competing activities, speaking negatively about the employer and criticizing them. The employee must not harm the employer, as it is commonly agreed that the employee should prioritize the employer's interests over their own.