I'm not sure why you think what I said is incompatible with this. Often the best "lie" is a carefully cut-out corner of a larger truth.
Because it’s literally the opposite. Misattribution is disinformation 101 if you have a solid source you need to protect.
US finds out China severely compromised a system while pretending to be Russia. The US found this out via a compromised Chinese government asset.
They need to fix the system but don’t want to let on they knew it was China and risk compromising their insider knowledge. Best course is to just say, “we found this that looks like Russia and we fixed it”.
There is no reason to assume a public attribution from an intelligence agency is correct. There are far too many reasons for it to be helpful to lie.
That’s... not how that works at all. Disinformation campaigns very frequently include publicly signaling you’ve come to a different conclusion than the real one you’ve come to.