Why do the original coordinates change when objects are merged and then separated?

After merging multiple objects, if I select “with structurally separated parts” and then separate them, each of the separated objects remains at the coordinates of the object it was merged with. Why is this? Also, what is the remedy?

When you merge objects, they take on a common origin. Separating doesn’t change the origin point. After separating, you need to set the origin point yourself- the easiest way is just to select them all and do Object > Origin to Center

If you add a particular vertex or vertices to a vertex group, you can reference that vertex group after merging and use it as a origin point, storage container.