Where are you seeing "Vega 8"? Post a screenshot.
Is it just the name of the graphics? Or are you experiencing an actual performance loss?
I have a 5700G which is Vega 8 but it is named "AMD Radeon (TM) Graphics"
Ryzen R7 5700X | B550 Gaming X | 2x16GB G.Skill 3600 | Radeon RX 7900XT