My sister married a US citizen and she was in the naturalization process before becoming a US citizen while she got her Canadian PR approved (she applied as skill worker many years ago). She landed in Canada and received her PR card wihch states that she is a citizen of country X. Now her US citizenship is approved and she changed her citizenship to US citizen, what will happen to her Canadian PR? Her PR card show that she is a citizen of country X but now she is a US citizen, so is the card still valid?