This site introduces unknown Emanuel Bach (C. P. E. Bach).
ChatGPT4o writes as follows (please note that it may not be accurate):
Emanuel Bachʼs Fantasia in D minor Wq. 114-07 (H. 234) is a work that showcases his emotionally rich expressiveness. This piece is characterized by its free form and improvisational elements, featuring sudden modulations and rhythmic changes that surprise the listener. Bach skillfully manipulates the flow of emotions within the music, depicting an inner drama. Notably, the contrast between tension and release is vivid, drawing the audience in. His music pursues new expressions beyond the boundaries of the Classical era, and this fantasia is an example of that pursuit. The flow of the music is unpredictable, offering new discoveries with each listen.