When I copy my project to a new computer, all objects in the world kept their name but was in a placeholder state with no object

I was trying to copy an old project, about a year ago and as the question says it made a placeholder like object that was just like a normal object in the world that didn’t have an object assigned to it, do anyone know what caused that or what i can do to prevent it? I copied the content folder from the documents folder and reopened it on a different computer or really the same computer after a factory reset.