I have a couple of lengthy posts on it, but I believe the HPFP problems are related to a lack of fuel from the in-tank LPFP, which results from low fuel levels compounded by a split tank design.
It appears the tank fuel level sensor and LPFP pressure sensor may be causing the LPFP to pump less fuel than it needed to keep the HPFP healthy. Software is able to modulate the speed of the pump, so to prevent HPFP problems I believe BMW modified the software to make sure the LPFP is always producing enough fuel - hence the additional noise.
Again not sure how annoying it is for you, but it's quite possible the pump is completely healthy, just louder.
