a conflict of interest idiom
C2 利益（或利害）冲突（因为相关自身利益而使当事人无法做出公正或公平判断的情况）
a situation in which someone cannot make a fair decision because they will be affected by the result
I need to declare a conflict of interest here - one of the candidates for the job is a friend of mine. 我需要报告一个利益冲突的情况——这份工作的候选人之一是我的朋友。