I think the source of the trouble is the tripod joint near the gearbox. GKN has a solution for SUVs with higher angles with 2 more or less normal cv-joints and a ball spline for axial movements.The source of the vibration is definitely the shaft. I think previously they just reinforced the Clevis to better absorb the shock generated when the shafts start to have the issue. Hopefully, the updated shafts resolve the issue (fingers crossed)
Why are Volvo using this solution for their bigger SUVs if the tripod could work? The cost is somewhat higher so I think they come to the conclusion that the tripod solution could not work!