I would download something like HWiNFO/GPUZ and see if they correctly identify the 8GB VRAM. Windows may not, but one of those should.
(ROG has simply become too expensive compared to the competition with same specs... 😞 )
MSI GE75 Raider 10SGS - i7 10750H - RTX 2080 Super - 32GB Ram - 1TB WD NVMe - 2TB 960 EVO - 300Hz 17inch Display
RETIRED: ALIENWARE R17 R5 - i7 8750H - GTX 1070 @ 1.9Ghz - 16GB DDR4 - NVMe 970 EVO 1TB - SSD 960 EVO 1TB
SOLD: ASUS G703VI-XH74K, RETIRED: ASUS G752VY-DH72, RETIRED: ASUS G750JH DB71 , RETIRED:ASUS G74Sx DH72