This site introduces unknown Emanuel Bach (C. P. E. Bach).
ChatGPT4o writes as follows (please note that it may not be accurate):
Emanuel Bachʼs piano piece for one hand, Wq. 117/1, is a unique work known as "Piece muta," included in the 1765 collection "Character Pieces." The title "muta" is derived from Latin, meaning "to silence" or "to quiet," and is thought to imply the special nature of the performance, as it is played with only the right hand. This piece is designed to showcase the technique and expressiveness of the right hand, characterized by its lyrical and graceful melody. It beautifully exemplifies the delicacy of the Empfindsamer Stil (Sensitive Style), requiring the performer to draw out rich nuances with just one hand. Despite its brevity, it is a technically and musically intriguing piece.