cn-gpu hashrate
vega 56 ~1750 H/s @ 1400+ core
https://imgur.com/a/YHsnqZJvega vii ~2300 H/s @ 1550+ core
polaris ~650-800 H/s @ 1150+ core
Have you compared the speed to Stak maybe?

Can you tell me what is the codename of vega vii ? gfx... ?
stak was around 1550 or so. Didn't try much of tweaks over there.
VII was 2100-2200.
polaris cards are a bit less too.
code name for VII is gfx906.