Very simple. You could contaminate freely on China, but not in Europe and USA. You can use as much coal as you want, with as many ashes, sulphur or radioactivity as you want.

That makes energy super cheap. But is is an external cost, people are paying with their health.

Europe and USA went to similar periods in the past. Now China is regulating more and more because pollution is a huge problem there.

Then you have salaries, that used to be cheap, now not so much.

Also a very important thing is that in China capital is not free, it is a communist system and your savings account are used to subsidise what the Government wants. EV, solar, electronic chips and batteries are a priority so they receive infinite amounts of money from Government.

Finally you have scale. China usually have enormous markets because it has so much people, although that applies to cheap things, for cars they don't have enough buyers inside so they want to sell in Africa and India and the West.