Switched to to 2.4GHz and you are right, I am having about 0.6%, less than on 5GHz. But difference is not that much and I am not sure that it's a bug (in my case).
Do you have access to any other 5GHz network? May be this problem is related to some Huawei specific issue?
I don't have any Huawei wifi hardware around at the moment but give me some time..