I’m not justifying imperialism. There are reasonable arguments to be made against Chinas actions.
The matter of fact here is that all of those regions listed: Tibet, Hong Kong, Macau, Taiwan. There are or were fought over as a direct result of external imperialism. Tibet had been a part of the Chinese empire for over a thousand years, and only emerged as an independent nation after a total collapse and state failure. There was a power vacuum for almost 40 years, and once a new government emerged, it retook Tibet.
Hong Kong and Macau only exist because of western imperialism.
It has been government policy for both the PRC and the ROC that Taiwan is a part of China for the last 70 years, only recently has Taiwan started to break from that.
All that said, I am now here trying to justify actions. Rather I am looking to contextualize. In the west we couch everything into a narrative of good vs evil, with the west being the good and moral force, and our enemies being the evil side. Reality isn’t so clean. And I am personally very disappointed to see the tenor of conversation around US China relations these days. Neither country is perfect and both countries have done things I think are wrong. I would hope that we can engage each other in a productive way rather than a destructive one, but more and more things seem to be going in the opposite direction.