In AURA if I remember correctly there is a page/section with sync at shutdown, set that as off.
I'm using UEFI 0804 and have no issue with RGB being off when motherboard is off.
To be honest even if in UEFI you do not set the setting to have RGB off in sleep/power off states, but set AURA to switch RGB off at shutdown it will apply.
I even uninstalled AURA after RGB set as I wanted and settings are kept.