How bad is US forecasting of China's military development? I doubt you have top secret clearance at the CIA or DIA. Nothing expressed in the US media is indicative of what the intelligence community knows.
F-22 production line was killed in 2009 because at the time, US intelligence said China won't have a 5th gen by 2020 and very few units by 2025.
Then just 3 years later in 2011, J-20 appeared on it's first test flight, a good 9 years before US intelligence prediction.
Now we are 2020, China is atleast 60-80 units, and by 2025, atleast
double-triple that amount, almost equaling the total F-22 in service.
Huitong seems to think that the image is authentic.
The exhaust tail section definitely looks photoshopped. The pixelation and differences in light reflection makes it obvious it's photoshopped.