吃别人嚼过的馍不香
chī​bié​rén​jiáo​guò​de​mó​bù​xiāng

to lack originality

吃别人嚼过的馍不香 吃別人嚼過的饃不香 chī​bié​rén​jiáo​guò​de​mó​bù​xiāng
to lack originality
literally meaning bread previously chewed by someone else has no flavor; used to describe how there is no satisfaction or value in merely repeating what others have already done or discovered