विपर्यये प्रत्यादेयः ॥ कZ_०९.४.०६ ॥
viparyaye pratyādeyaḥ
In the opposite case, it is ‘pratyādeya’ (a gain that must be returned/restored).
If it is hard to obtain or hard to safeguard, or is liable to rightful claim and restitution pressures, it counts as returnable.