They’re a thing but they’re heavily overblown by Western media.
With regards to the sweatshops, China is the only place they actively shit on the state itself for the existence of sweatshops. You never hear them blame the governments of Bangladesh, Indonesia, Nicaragua, Egypt etc for the sweatshops (which you shouldn’t, sweatshops are the fault of the corporate dickheads that use them). It’s the same thing with the allegations of slavery, they don’t mention the governments of Ghana or Congo for the slavery in harvesting Cocoa or Cobalt (and these governments are more at fault for the existence of these things because they are usually puppets for the West and knowingly allow this).
These people are mostly also just out of touch with rising working standards in China. 996 is bad but it’s actually being combated by the central government and also apparel companies such as Nike have already moved most of their manufacturing for textiles out of the country to places like Bangladesh and Indonesia. Most of the production they keep in China is due to the comparative advantage of China’s infrastructure and supply chains that overrides the cost of greater exploitation of the workers of lesser developed nations.