Sure. They do not drop 60% in only a few years, only amongst a single ethnic group in a single region. The numerous testimonies, plus recently leaked documents confirming this is an explicit CCP policy removes any doubt.
The testimonies are a strong argument, however we're in the middle of information war against China. There is also the argument of the amount of those testimonies: there are surprisingly few of them, given millions of people armed with smartphones who live there.
That's just one possible explanation.
But the premises of 60% drop in birth rate from 2016 to 2918 is not verified in the first place...
I am still asking the source of 60% drop in birth rate of Uyghur groups. You probably need similar data for other ethnic groups to prove that this drop in Uyghur is unusual.
The point remains that no one is applying the same standard when discussing China related issues. Why birth rate drop is linked to genocide? Because it's China!