Changes of government don’t mean an entirely new country...
Yeah, it kinda does. The words "Country' and "Nation" aren't full synonyms even though people tend to use them interchangeably. A a Country is a political entity while a Nation is focused on the collective identity and shared values of its people.
In short the Nation of France is old while the Country of France is much younger.
The definitions honestly feel backward to me but I'm not the person in charge of these things.