Is plucking a single eyebrow hair by mistake considered a sin that warrants being cursed, and what is its expiation?

Plucking the eyebrows falls under "al-nams" (plucking of eyebrows), which is forbidden in Islamic law for both men and women. Atonement for this sin is achieved through sincere repentance, a firm resolve not to return to it, and increasing acts of seeking forgiveness (istighfar) and righteous deeds. For Allah accepts the repentance of those who repent, believe, and do good deeds.