So, I have a bike with a Bafang geared hub motor, fairly new but been over some rough terrain. Under certain conditions (load, speed) it'll whine while the motor is active. I'll stop pedaling and it'll keep whining right until the pedal assist "times out" and the motor is no longer powered.

I don't see anything on the outside that's loose or anything. My best guess is that there's something inside the motor that's loose and touching something else when the internals are moving just right. But I haven't been inside one of these things to know if that could be true.

The motor works fine otherwise.

Audio, starting around 24s: https://www.youtube.com/watch?v=-qJcDH3h5Mc

There's some other extra noise I'm hearing, but it may be related and most annoying thing first.