I’m aware.
But practically, that’s a difference without distinction. The majority of the rest of the world considers Taiwan to be a sovereign nation, and Taiwan has been acting as such for a long time. Functionally, that argument is the same as Russia is making with Ukraine, and technicalities over academic language doesn’t change that.

North Korea and South Korea are de facto separate countries, even though their civil war technically didn’t end. If the south invaded the North, that’d be the same.