Yes citizenship by birth has been applied against people’s will, and with serious consequences. In fact my son may actually have unintended and unwanted dual citizenship. The problem is we won’t know until we go to Korea after he is 18-20 or we spend some time and money to renounce citizenship he may or may not have. Here is the deal as best I have grasped it.
My son was born in USA mom was still a resident alien and so a citizen of Korea. By Korean law he is also a Korean citizen, but only if someone added him to the family registry in Korea, and we have no way of knowing if a relative added him to keep the registry complete and up to date without the knowledge that that would make him a citizen. Here is why it is a problem, if he is a Korean citizen, even without knowing it, and visits Korea during the age where male citizens are required to do 2 years of army service, he can be refused the right to leave the country and drafted into the Korean army for 2 years.