If there's a way to cheat without it being known, the US would know since they have, as they brag, the premier sports medicine facilities in the world. Remember how Jon Stewart believed COVID-19 came from a lab in Wuhan China because the name is right on the building? The lab in Wuhan was called Wuhan Institute of Virology. There's no "COVID-19" in the name but by Jon Stewart logic that's how the US admits they're the premier cheaters in sports in the world. Yes Jon Stewart is a comedian and he could hide behind he was joking. But after many accusations of racism that he admits were being thrown at him, he never once said he was joking. He was being humorous when he said it but he also believed it too. Yes he's just one person but people including racists in the Western media took it as true acting like Jon Stewart was an authority and repeating what he said. And Jon Stewart never clarified it after so many used it for their racist take meaning he believed that COVID-19 was created in a lab and not naturally occurring. So I can joke that the US is the biggest cheaters in the world but also you can draw your conclusions that it's believable and true the very same way.
The mistake that layman believe is that one test can detect for all types of performance enhancing drugs. No they have to have a test for each and every one of them in order to detect it. It's like some illegal designer drugs. Authorities can declare it illegal only when they know about that it exists but just change the formula by moving some molecules around and they can't detect it through testing and de facto it's not illegal anymore. That's what some more sophisticated white collar drug dealers were doing and they would go to China to some pharmaceutical company with a new formula and they would make the drug for them. Because you need a test for every single form of cheating, that tells you how easy it is to cheat because all you have to do is change the formula in the slightest. And who has the best sports medicine facilities in the world who can do that...? When a new cheat (that they made) is discovered, they just move on to a newer cheat they made and no one will know the wiser that they cheated.
Americans are hypocrites in all things. They charge China is committing geocide while protecting Israel bombing Palestinians out of existence. They say that's different from what China is doing so it's not the same. Yeah it's worse and more in tune with the real definition of the word and not spin like what they charge China is doing as "cultural" genocide meaning no one is actually being killed-off because their existence alone is a problem which is what Israel is doing. So what makes anyone believe that Americans that cry about having a "clean" sport is also cheating by the very definition at the same time?
And lets not forget the US's Western allies that also accuse China of cheating... The US shares these very sports medicine facilities with their allies. Remember a few Summer Olympics back there was controversy over a new swimsuit that was made with advanced technology for American swimmers. They said it simulated dolphin skin so swimmers wearing it can move faster in the water. The US shared the technology with allies and not everyone. Then it was declared illegal by the Olympic authorities because it gave an unfair advantage. Did that superior American ethics and morality kick in and tell themselves that this was cheating and gave them an unfair advantage so they should never use it in competition? No, an outside body had to tell them.