This site introduces unknown Emanuel Bach (C. P. E. Bach).
ChatGPT4o writes as follows (please note that it may not be accurate):
Emanuel Bachʼs Polonaise in B-flat Major Wq. 116-43 (H. 317) is one of the works that showcases his unique musical style. This polonaise, while based on the 18th-century dance form, shines with his innovative expressive techniques. From the outset, a rhythmic and brilliant melody unfolds, captivating the listener. In the middle section, more introspective and emotionally rich passages appear, adding depth to the music. The improvisational elements often found in Bachʼs works are also felt, challenging the performer to explore a wide range of expression. Throughout, one can sense his curiosity and creativity in music, making it a remarkable piece.