We follow the original Japanese broadcast where it was broadcasted without seasons split. Story arcs aren't seasons.

Ok, thanks for your reply. But my question now becomes: why is Dragonball Z divided into story arcs? It was also broadcast in Japan without interruption (and therefore I assume without division into seasons) from beginning to end, such as Dragonball. It seems strange to me that only Z was divided while Dragonball, GT and Super were not... Am I perhaps missing some information?

If you read the content reports of that series, you can can read that the seasons will be merged at a later date, not yet defined, by the administrator.