Three Dimensional Geometry: JEE Main 2021 Mathematics question

Let the line L be the projection of the line ${{x - 1} \over 2} = {{y - 3} \over 1} = {{z - 4} \over 2}$ in the plane x $-$ 2y $-$ z = 3. If d is the distance of the point (0, 0, 6) from L, then d² is equal to _______________.