As we can see, at t = 0 --- both diagrams are fine.
But for t = 1 and t = 2 the top and bottom diagrams clearly show two realities.
In the top diagram, the light emanates from the middle of the carriage at t = 1 and t = 2.
In the bottom diagram, the light emanates to the left of the middle of the carriage at t = 1 and t = 2, which is impossible.
We can't have two realities.
So something is amiss with this figure.
Also, the optical rays are the same length in both figures. This is not the case in the Einstein Light- Clock, in which we have different ray lengths in the moving and stationary systems.
So again, something is amiss, in the above figure.
https://en.wikipedia.org/wiki/Relativity_of_simultaneity