China stopped testing ages ago and has censored anyone questioning the current government's narrative (and has arrested doctors, medical professionals, and random people on WeChat).
This is one of the problems with comparing Covid statistics between countries. The US, for instance, counts a death as 'Covid' if they died of some other cause, but had Covid symptoms. In other countries, these aren't counted. it's not just Covid stats where this is a problem. Crime stats are calculated in completely different ways in different countries and used as ammo in political discussions.
The US has been continuing to test, so our numbers are going to go up as more cases are detected. Countries like Iran, China, Vietnam, and Mexico aren't really doing any sort of testing besides spot checking.
These numbers are being used to politically crucify the current administration, when it's a completely disingenuous comparison.
On top of all of this, the Covid death rate per-capita of the US is one of the lowest in the world. Too many people don't understand why you can't directly compare a country like South Korea (population: 50 million) and the US (population 350 million).
Here is a good link from Johns Hopkins: https://coronavirus.jhu.edu/data/mortality
The US is at the low end of Covid death rates. I don't trust Iran on this chart, because it's already pretty well known they have been lying about their numbers.