Do many Vietnamese people think Southern China is Vietnamese?

 In Vietnam, people are taught this map.

The people are taught that the tan colored part labeled Vietnam belongs to - you guess it - Vietnam; and the parts not tan colored are not Vietnamese land territory.

You see that arrow pointing to that circle , that’s Southern China. Now, as you can see, it is not tan colored, it is red.

Vietnamese people see this, and use their logic.

“Since parts of the map that is tan colored and is labeled ‘Vietnam’ is part of my country, and Southern China is red, not tan, then that must mean Southern China isn’t part of Vietnam.”