What does Bias wrecker mean in K-pop?

The member who keeps tempting you away from your bias.

A bias wrecker is the member who threatens to replace your bias. You still love your bias, but this member keeps catching your eye.

Korean fans use cha-ae (차애), meaning "second favorite." The English term adds a playful sense of danger.

“I came for Jungkook, but V is a serious bias wrecker.”