They say that my country of origin (Uk) should have been responsible for the last 17 years. The UK say definitely not. The insurance company sent a lot of premiums back and then said I'd have to pay for the cost of treatment over the years, which has been expensive - among other things, two very bad pregnancies with hospital stays.
I appealed it to the Dutch 'social insurance department' who said that I was insured from 2020 onwards but still might not have been insured from 2007 - 2020 (so, thirteen years as it turns out, but the insurance company tried to establish a claim from 2007 - 2024).
On Friday the 'social insurance department' lawyer is talking to mine and my lawyer's given them some European legislation that means I should be ok. But if they decide against me, then to court it will have to go, and 6 months' uncertainty.
But the NL is a country that does have the principle that everyone should have access to health care insurance even if the insurance company ferreted out a tiny loophole that I've fallen through, which is why I can appeal to the govt 'social insurance department' and if that doesn't work, can take it to the European Court of Human Rights.
In the US there isn't that basic expectation as far as I'm aware. Hence the appalling actions that some health insurance companies can get away with.