The FBI was investigating Carter Page in 2016.
Yahoo news reported that members of the US intelligence community were investigating Carter Page, a member of the Trump campaign in September.
The FBI is part of the US intelligence community.
As a member of the U.S. Intelligence Community, the FBI collects, uses, and shares intelligence to carry out its mission.
www.fbi.gov
So yes, the FBI’s investigation into the Trump campaign was public knowledge before the 2016 election.
You are wrong. And it’s bizarre that you keep harping on this.