Is this a glitch or a mistake?
Its a misunderstanding. The moon ball has a higher catch rate on Pokemon that evolve by moon stone, but the ball itself does not evolve them. You still need to use a moon stone to evolve then.
You need to use the Moon Stone on Nidorina in order to evolve it into Nidoqueen.
You evolve Nidorina into Nidoqueen with a moon stone not a moon ball.