When clearing / regenerating Network IDs for worlds Player Object Data gets cleared (due to the difference in Network ID) and if the creator doesn't know the original Network ID of the Player Object they don't really have a way to know what it would have been.

Maybe something like logging the Network IDs of all Player Object Data when the world loads and also logging if the ID attached to it is missing would be helpful for recovering the ID in a situation like that.

(Not quite sure this is how the Persistence systems works 100% internally so I'm not sure if this implementation would work like this)