B&W speaker cover makes noises

I was really happy when my new XC60 2 was finally free of flaps and knarz noises. Now, after half a year, it starts here as well: the silver loudspeaker covers of the B&W system (in the two front doors) clutter. In basses the apertures are significantly louder than the music, and even at medium volume. Depending on the road surface, the squeaking can also be heard continuously during the ride – in case of unevenness anyway – even though the music is off. The most annoying thing is with audio books, because the mostly male speakers constantly cause the covers to clutter. The peculiarity is that the apertures are absolutely fixed on the outside. There is definitely a temperature dependence: when the car is warm, it is clearly worse. My friend says the problem is known, and there is also an official remedy from Volvo against it. Various parts of the door panel were replaced, however, and that is my problem: with exactly 0 success. The repair has absolutely nothing to do with the noise of the speaker.