I agree, it can’t be any other part of the computer or OS.
It’d be one thing if it was impossible to cut the USB power in general, but I’ve used these ErP and CEC2019 settings for years before the latest BIOS update I did.
As I seem to understand it, some people online with certain other Gigabyte motherboards have reported ErP settings not taking after certain updates. If nothing else comes up I’ll have to reach out to Gigabyte to inquire.