This is going from memory… I believe archaic Latin could be written left-to-right or right-to-left (same with some of its alphabet ancestors like archaic Greek) and the direction of the letters was often dependent on the direction of the script. So they could really be written both ways. When Latin became predominantly LTR instead of RTL, the direction of the letters essentially changed.

Here is the YouTube video that accompanies this chart. He might explain it there, but I don’t have time to watch it right now.