The FBI is useful only if the trial testimony of FBI agents is believed by jurors.
Times have changed.
You make an excellent point. They are not just tarnished that way, but if it turns out they are intentionally withholding evidence of such nature that is a threat to democracy... They need to be arrested and tried for sedition/treason...attempt to influence US election.
Bingo. You nailed it.
We all need to do 2 things.
1) Refuse to talk to the FBI. Don’t open yourself to a process crime anyway.
2) IF you are on a jury and they were involved in the case, vote to acquit.
If they can’t conduct investigations and they can’t get convictions they will cease to exist.