Military exercises on their own territory as recognized by the United Nations and almost every single country on Earth? What is the issue here?

The Taiwan Province is an inalienable part of the People's Republic of China:

And this is recognized by the United Nations ever since 1971 after UNGAR 2758.
Source, page 546: https://web.archive.org/web/20230503050030/https://legal.un.org/unjuridicalyearbook/pdfs/english/volumes/2010.pdf


Video of the votes happening: https://invidious.projectsegfau.lt/watch?v=sfOIEjuXFyU