Elephant Ear-Like Plant Decline: Need More Details

Eryl's large "elephant ear" plant developed black spreading on one giant leaf, while new leaves yellowed and wilted after repotting and regular watering in a sunroom.

Missing Information Needed

• Exact plant ID: Many plants resemble elephant ears but have different needs. A photo would help.
• "Black spreading" description: Is it mush, spots, fuzz? Texture and pattern matter.
• Light specifics: Distance from window, window direction, hours of direct sun.
• Watering definition: "Regularly" is vague – frequency, amount, drainage?

Likely Issue: Repotting Shock

Repotting a new plant is rarely advised and often causes root disturbance leading to decline.

Please provide details for a precise diagnosis.