In Jainism, we have to be very precise here.

1. Two main types of Samyaktva (Right Faith) Jain Acharyas distinguish:

1) Vyavahār Samyaktva – practical / conventional right faith 2) Niścay (Aupśamik / Kṣāyik) Samyaktva – absolutely steady right faith (from higher guṇasthānas)

Can it be “eclipsed” (lost)?

a) At the lower stages (vyavahār samyaktva): Yes.

• When a jīva first attains samyak darshan (from 4th guṇasthān), if the underlying darshan-mohaniya karma is only suppressed (upśama) or partially destroyed, then fall-back is possible.
• By strong passions, wrong company, pride, greed, etc., such a person can lose right faith and fall again into mithyātva (wrong belief).
• This is why texts speak of samyaktva being disturbed or broken (bhang) by rise of mohaniya karma.

So, in this practical sense: Yes, samyaktva can be eclipsed / lost if it is not kṣāyik (fully destroyed).

b) At the highest form (kṣāyik samyaktva): No.

• When darshan-mohaniya karma is completely destroyed, the soul attains kṣāyik samyak darshan.
• From that point, there is no return to mithyātva, no more eclipsing; right faith is permanent for that jīva.
• This belongs to the higher guṇasthānas and leads steadily towards keval-jñān and moksha.

Short answer

• Ordinary / initial samyaktva (based on suppression or partial destruction of karma) can be eclipsed and lost.
• Perfect, karmically destroyed samyaktva (kṣāyik) can never be eclipsed.

If you want to read a simple explanation of mohanīya karma and how it disturbs samyaktva, you can see this discussion here: