I have the same issue. When playing and holding a certain chord, it makes a weird flapping helicopter-like noise. I recorded it:
https://youtu.be/USDXEE2MiC0
It does not happen with non-piano sounds, and it does not happen when pressing the keys softly. It is not related to pedals or overall volume.
Does anyone have an idea what could be the problem, how it could be solved or which part would have to be replaced?