A better example would be having the confederate flag. Except that the confederacy being dissolved is already a decided issue at the national level. (Also most Americans are only familiar with the confederate army flag, and not the confederate national flag.)
China and Taiwan have no such agreement. Taiwan says one thing, mainland China says the opposite. There is no resolution.
I’m a dual citizen of Canada and the US. But I also know that if there’s a language selector, and I see the British flag, I know it’s gonna get me English.
Perfection is impossible when human beings are involved.