I mentioned the Huns in a previous post and here is one part why things go overboard.
Once upon a time they had the UA unit capture ability (now its a French UA) and UU horse archer with focus fire, now they have the to old french UA ability which is same as horse archer focus fire.
However that was not the only Hun UA they also have gold+culture on city attack and extra war weariness, so basically 3xUA.
Its sort of easy to just kill all opponents with mass horse archer > heavy skirmishers (on emperor).
With city healing and amount of hp the gold/culture from city attack is massive.
Attack enemy with a bunch of horse archers and then go with the siege last for massive extra bonus.
So the horse archers double dip, as you see in picture, second horse archer gets +20 (+10 from UA and +10 from UU), this is correct but maybe the horsearcher promo was forgotten when the UA got swapped around.
I may be incorrect or overthinking and things will probably go bonkers with 4UC anyway but maybe put 3xHun UA on a list of things to oversee.