Overnight eggplant is edible if it has not spoiled.
Overnight eggplants can be eaten if they are properly preserved, e.g. by better preservation methods such as sealing in plastic wrap and keeping at low temperatures in the refrigerator, if the eggplants have not deteriorated (no odor, no bacterial spots, etc.), and if they have been adequately processed (e.g. by heating, etc.).
However, if overnight eggplants are not properly preserved and deteriorate, some of the nutrients (e.g. vitamin C, etc.) may be oxidized by oxygen and other components in the air, thus losing their original nutrients, and secondly, deteriorated eggplants can have a large number of microorganisms multiplying, which may cause gastrointestinal discomfort after consumption.
Therefore, overnight eggplant can be consumed if it is not spoiled. If you feel sick after consuming it, you should go to the local hospital immediately.