Disc brakes making a banging sound on steep descents
Possibly calliper alignment. Manufacturing variation in hub or badly faced rotor mounts can move the rotor plane in or out a crucial tiny amount which combined with a odd calliper shape can result in some of the arms of the rotor bonking the calliper under the right conditions. Hence the thunk, thunk sound. Not dangerous but annoying.
Moving the callipers a touch to one side (e.g use a paper width as a gauge) might fix the issue without significantly affecting the centering.