According to Footnote 302, in October 2016, FBI investigators learned that one of Steele’s main sources was linked to the Russian Intelligence Service (RIS), and was rumored to be a former KGB/SVR officer. However, the FBI neglected to include this information in its application, which the FISA court approved that same month. Two months later, investigators learned that Glenn Simpson, the head of Fusion GPS, told a Justice Department attorney that he assessed the same source “was a RIS officer who was central in connecting Trump to Russia.” In January, the FISA warrant was renewed.
Footnote 350 states that, in 2017, the FBI learned that intelligence reports “assessed that the referenced subset [of Steele’s reporting about the activities of Michael Cohen] was part of a Russian disinformation campaign to denigrate U.S. foreign relations.”
That same footnote (footnote 350) states that a separate report, dated 2017, “contained information … that the public reporting about the details of Trump’s [REDACTED] activities in Moscow during a trip in 2013 were false, and that they were the product of RIS ‘infiltra[ing] a source into the network’ of a [REDACTED] who compiled a dossier of information on Trump’s activities.”
https://www.grassley.senate.gov/news/news-releases/fbi-ignored-early-warnings-debunked-anti-trump-dossier-was-russian-disinformation