Sundering of Zodiark

[Yukijin]

(...)But they're never quite clear about what it means for "the fragments of His power" / "His Darkness" to be spread throughout the dimensions. Or where the cosmic tear stops. Or if all the skyboxes in the game are accurate. I think we still have a lot of questions.(...)

For me it would make sense for the moon on each shard to have a piece of Zodiark in order for him to enact his power towards what was revealed to us in Endwalker
Additionally, It would also make sense to me for the moon to have existed before the sundering and Hydalin just repurpose it as a Prison to Zodiark, hence all shards would have a Moon regardless of it having or not a piece of Zodiark on it