이유가 뭘까

what could the reason be?

→ 이유
phrase Rare #28,573
what could the reason be? A casual way to wonder or ask what the reason is.
KO: 요즘 손님이 줄었어. 이유가 뭘까?
EN: There have been fewer customers lately. What could the reason be?

이유가 뭘까, 벤야민?

What is the reason, Benjamin?

— 엘 시크레토: 비밀의 눈동자 (2009)

이유가 뭘까?

What is the reason?

— 포풍추영 (2025)

실력은 있는데 못 크는 사람 이유가 뭘까?

Why do some people have talent but never reach their potential?

— Kill Boksoon (2023)