First, I make no claim that the 4x or 20x numbers are true. Sans an investigation, any such claim should be viewed with suspicion. However, the claim that financial irregularities are almost certainly there can't possibly be controversial.
If I was forced at gunpoint to point out the obvious, Ukraine was one of the most corrupt countries in Europe prior to the war. Unless you are saying that - magically - the people who were syphoning money and treasure from the Ukrainian people were all killed or "vanished", the same appetites for corruption still exist while large amounts of resources are being poured in. This is literally the opportunity of a lifetime for aforementioned bullet-stealing bloodsuckers.
The US has never been good at tracking money or getting value for money. Even during the Civil War, Union capitalists initially looted the Union with broken weapons and badly made uniforms. Haliburton is a more recent example of this poopstain on the American economy.
While the amount of corruption is in question, given the above two, there is every reason to believe financial corruption is happening. Those who disingeously pretend everything is normal are frankly suspicious.
Honestly, I can't believe I need to make this clear in a discussion about "War Is A Racket". Then again, a weaker, poorer America that isn't able to murder brown people for fun and profit is in my personal benefit, so maybe your ignorance is beneficial. Yes, please don't investigate; any such suggestion was clearly made by Russian bots.
I wonder, too, if you would be doing the same thing if you saw a russian missile flying towards you.