Let’s say I become a citizen of a country that doesn’t allow dual citizenship. During naturalization, new country B tells me I have to renounce citizenship from old country A.
Does that have any effects back in country A? How would country A know? Would country A even care if they found out?
Like others have said it depends on the countries, for example Argentina as the country A is impossible, because Argentinian nationality is irrevocable as per the constitution, so if you’re born in Argentina you can sign any paper county B asks, and they will get dutifully ignored by Argentina.