favouritism 偏爱

favouritism n. 偏爱
the practice of giving unfair preferential treatment to one person or group at the expense of another.

Example:
Even the strictest codes can't really prevent favoritism and bad decisions, because the ultimate decision is always made by an elected city, town, or county council or commission.

Favoritism in the workplace: favoring someone not because he or she is doing a great job, but for reasons outside of the job performance. Oftentimes, favoritism occurs when a manager and an employee have developed a friendship beyond the workplace. Examples of favoritism in the workplace are when two coworkers worked together previously and have a shared history, or maybe they have bonded over common outside interests, like sports or music.