It's ironic that China proclaims itself as communist but works so hard to suppress things like... you know... labor movements.
That’s how they’ve operated in eastern bloc countries. The workers’ unions were controlled by the party. They were not free to protest, etc. They were there to coopt the workers, essentially.
By the end of 1976, virtually all communists were purged from power in the PRC. Mao Zedong had said Deng Xiaoping wanted to take the capitalist road, and when he took power, that's what he did.