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 B-flat Major Wq. 112-08 (H. 146) is a work characterized by its strong improvisational elements and unfolds in a free form. This fantasia is notable for its unpredictable modulations and rhythmic changes, which surprise the listener. The piece vividly reflects his musical philosophy of "expression of emotions," demanding high technical skill and sensitivity from the performer. The melody is often adorned with ornamental notes, offering rich expressiveness. Positioned between the Baroque and Classical periods, this work exemplifies Emanuel Bachʼs innovative musical vision. While influenced by his father, Johann Sebastian Bach, it also establishes his unique style.