It is not a customs charge as such - it is the new tariff charge introduced by Donald Trump.
Anything you now sell to the USA will involve such a charge - the baseline charge is 10%.
It is up to the seller to pay it and it is unavoidable - the only way to avoid it is not to sell to the USA.
"There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.”
Søren Kierkegaard, Danish philosopher (1813 - 1855)