Overpopulation isn’t defined by how much people there are, but by the total amount of sustainably produced goods and services divided by the total population. Fewer people producing unsustainably would also be overpopulation. We need to transition to sustainability regardless of amount of people, reducing population only leads to slower decline, not to a stop of it.
You don’t need to use China for the superlative of bad work conditions when you’re talking about bad working conditions in the US.