i suggest check the rear parking brake shoes clean and lube the retaining springs with WD40 silicon. very recently encountered same whining issue in a 2018 32000 km old vehicle MT guys were skeptical with bearings noisy at high speed. However it turned out the rear parking brake shoes were bit sticky not returned to default zero. removed the assembly cleaned, springs lubed with silicone problem solved. 1200 kms added over odo no complaints