There's no definitive answer, really.
No one's really sure how these drugs precisely work. They have different effects for different people, even if for things like depression and anxiety they nearly always offer improvement.
For something so elusive as DP/DR, their effects can vary. For some they help. For some they make it worse. For many, there's no change.
So the only answer I can really give is that it's perfectly "normal" for Zoloft to make DP/DR worse, since the effects it has in this area can vary. Some unfortunate folks, who were previously healthy, have got DP/DR just from taking these pills.
Don't worry about it, and stop or change medication if the problems with it continue.