Moksha is impermanent.
Caution: There is probably no Astika darshana that says that Moksha is impermanent, to the best of my knowledge. All darshanas believe that moksha is permanent. None of the Acharyas quoted below say that moksha is impermanent. However, their views will be quoted to support the idea that moksha is impermanent.
Point 1. ...
Moksha is like drop of water getting back to the ocean. Is it possible to take that exact drop of water out of ocean again? No. Once an Aatman attains Moksha, It merges with it's parent Brahma and there is no turning back.
In Taittiriya Upanishad, 3rd chapter
‘Bhrigu the well known son of Varuna Deva approached his father
Varuna with a formal request: ‘ ...
No, the Moksha state is independent of time.
Moksha only stable value
One who aspires to overcome the thick darkness of ignorance should
never seek contacts that are contrary to the fourfold end of life
(Dharma, Artha, Kama and Moksha). Of these four ends, Moksha alone is
accepted as the really stable value to be sought; for the other three
are subject to ...
Although many sadhakas go through what you describe, what you describe is auxiliary to achieving liberation - and not the means to achieving liberation. The direct cause of liberation is the direct knowledge of the Reality. Sri Vidyaranya Swami writes in his Pancadasi Chapter VI (Swami Swahananda translator):
Of all the three virtues the most essential is ...