Hello I'm trader. At previous alliance all traders we have 22 percent charisma on alliance representative..

You've witnessed something called a coincidence.

You changing alliances didn't lower the percentage of the trader's card buffs. The devs recently provided a patch that significantly lowered the value of these cards. You must've changed alliances at some point during this change, but rest assured, you are seeing the new normal.

As with any other changes you may dislike, you are always welcome to contact the developers and let them know your thoughts on in game updates. I feel that they are getting much better at listening to customers these days.