Underwatering
The plant has been dry for long enough that cells have lost turgor and leaf tissue is starting to die back at the margins. Drought-tolerant species forgive this; thirsty species like peace lily or fiddle leaf fig do not.
Based on what you've described, these are the likeliest causes — ranked. Each one carries a tell-tale sign that distinguishes it from the others, and a single-minute check to confirm.
The plant has been dry for long enough that cells have lost turgor and leaf tissue is starting to die back at the margins. Drought-tolerant species forgive this; thirsty species like peace lily or fiddle leaf fig do not.
Persistent soggy soil has killed part of the root system, and the fungal infection that follows is now attacking what's left. It's the advanced stage of overwatering: the plant is wilting because it physically cannot pull water up anymore, even from wet soil.
The soil has stayed wet for too long, suffocating the roots and weakening the plant from the base up. It's the most common reason houseplants decline indoors, and it looks deceptively similar to thirst: a wilting plant in soggy soil is almost always drowning, not dry.
bone-dry-soil--wilting