Those jiva-souls who fall to being called the "tatastha-sakti designation" means they have fallen (entered) the material world.
Srila Prabhupada - "So this temporary material world is the taṭastha (materially conditioned) characteristics, and the spiritual world is the permanent (personal) characteristics. So our effort is to get out of this taṭastha (materially conditioned) characteristics and enter the permanent (personal) characteristics. That is called spiritual elevation." (Lecture CC Madhya