No, they arrested a Russian CITIZEN - a woman who just so happened to become a dual citizen with US citizenship in 2021, for donating money to an enemy of Russia DURING a war.
Her becoming an American citizen is irrelevant since she kept her Russian citizenship.
What will the US do if an American citizen gave money to its enemy during a war? What do you call giving money to an enemy during a war? Isn’t it treason? And what is the penalty for treason?