In July, Buma sent the Senate Judiciary Committee a 22-page statement full of eye-popping allegations, and the document leaked and was first reported last month by Insider (after a conservative blogger had posted it online). According to Buma’s account, Giuliani was used as an asset by a Ukrainian oligarch tied to Russian intelligence and other Russian operatives for a disinformation operation that aimed to discredit Joe Biden and boost Trump in the 2020 presidential race. Moreover, Buma says he was the target of retaliation within the bureau for digging into this.
The complaints about the hoax are about the Steele Dossier which was “leaked” just before the election and disproved- as well as being at least partially financed(to the amount of $168,000) by the Clinton campaign.
Oppo research is standard operation procedure, so not sure how that is relevant. Also, what part was disproved?