This is a type of aphasia where formerly healthy children 3-7 lose their ability to comprehend and later speak language:

Landau-Kleffner Syndrome is characterized by the loss of language skills in children who were previously developing normally. This condition typically affects children between the ages of 3 and 7 years. Initially, they may experience a sudden or gradual decline in their ability to comprehend spoken language, and over time, they may also lose the ability to speak. The exact cause of this syndrome is not fully understood, but it is generally believed to be related to seizures that affect the language centers of the brain. In contrast, the other types of aphasia mentioned generally pertain to adults who have suffered brain injuries or strokes and do not typically apply to children in this way. Thus, Landau-Kleffner Syndrome is the most appropriate term for this form of language loss in otherwise healthy young children.