Taiwan is not China. Where in China is TSMC building cutting edge semiconductor fab?

Comparing Taiwan, which has been functionally independent of the PRC and under control of the ROC since 1945, to South Ossetia or Transnistria is absolutely ridiculous. Just because Taiwan isn't widely recognized by the international community doesn't mean that it isn't an entirely separate socioeconomic entity. A brief glance at the last two decades of politics in Taiwan will show you as much.

The UN is totally irrelevant here. Taiwan operates as an independent country in every practical way. (So does Hong Kong, kinda, but Taiwan even more so.)

TSMC fabs are mostly in Taiwan, not China.

And Taiwan would never let those fabs go to China, they have plenty of laws against that. Only oldish fab tech can be exported to the Mainland.

To clarify, by "China" I mean People's Republic of China, not Republic of China (which is usually called Taiwan).