From PsyPost.org:
Imagine looking at a loved one and seeing their face twist into a demonic, unnatural shape. Their eyes might stretch to the sides of their head, their nose might swell, and deep, unnatural grooves might appear across their cheeks and forehead. This terrifying visual experience belongs to a rare neurological condition known medically as prosopometamorphopsia.
In popular media and online discussions, it is sometimes referred to as “demon face syndrome.” People with this condition see human faces as severely distorted, even though their vision for everyday objects remains completely normal. Demon face syndrome is a jarring and often frightening condition that radically alters how a person experiences the social world. It strips away the familiar comfort of a human face and replaces it with something surreal or deeply unsettling. At the same time, it offers neuroscientists a brilliant, albeit accidental, lens into the sheer complexity of human vision.