Tatastha-sakti refers only to those jiva-souls who are already in a fallen condition, meaning those who are "conditioned" in the material creation, and who further fall to the dormant (inactive) impersonal Brahmajyoti.
In other words, tatastha-sakti does not describe those jiva-souls in their original "none-fallen" position in Vaikuntha and Goloka Vrindavana.
Tatastha-sakti is a name describing the none Krsna conscious condition of the fallen jiva-souls.
Srila Prabhupada - "So this temporary materi