In the Black Panther movie, N'Jakada's successfully challenges T'Challa and becomes King of Wakanda. He also attempted to widen the scope of his challenge to also include T'Challa's role as the Black Panther.
N'JAKADA: I am N'Jadaka, son of Prince N'Jobu. [...] I'm exercising my blood right to challenge for the mantles of king... and Black Panther.
In the customary ceremony before the fight, T'Challa is (for the second time in the movie) separated from the supportive power of the Black Panther.
N'Jadaka clearly becomes king, but it is unclear to me whether he becomes Black Panther, or whether T'Challa later somehow regains the power of the Black Panther. Who, if anyone, held the mantle of Black Panther after N'Jakada's successful challenge?