Its too wet.
Cuprea is considered a Jewel Alocasia. They don't like to be kept wet. Remove the moss ASAP, and don't add any more water to the soil until its almost completely dry
It MAY go dormant. If it defoliates, keep in in the warm sunny place. Don't fertilize it hoping to spur new growth.
If it resprouts and starts growing again, don't overwater it.
