They would not be able to hide infection on the level that the US has had it - antibody tests from travelers from China would show it trivially, social media would show it.
The idea that China has secretly had 3 million covid deaths and widespread infection without anybody realizing is a conspiracy theory.
As I've said, it would be obvious from antibody tests if they did this.
Not going to keep responding, you are letting your feelings about China's government cloud your judgement on the facts.
You’re saying the firefighters (WHO and the Western response) didn’t do enough to put out the fire burning down their houses (western countries), while simultaneously praising the neighbor (China) who found the fire, lied about the fire, “disappeared” people who attempted to report the fire, delayed response to the fire, spread the fire, but FINALLY at the eleventh hour made sure their own house didn’t burn from the fire.