Again, the situation is exactly like Germany and Korea. China is currently split and this is an issue of reunification.
Taiwan is part of China and the last territory of the Republic of China, whose government was kicked out of the mainland by the communist. Today is national day in Taiwan and that commemorates the fall of the Empire and the founding of the Republic of China...
Now, some people in Taiwan are opposed to reunification because of the current regime on the mainland, some are opposed to reunification full stop and want Taiwan to remain an independent country. That's the factual situation.
But calling into question the term 'reunification' is purely propaganda in order to paint the PRC as trying to invade a foreign country like if they wanted to invade Vietnam or another neighbour. From the West's POV this is a standard divide and conquer strategy.
