I believe, from the political weaponization of the agency in the recent past, that Trump is justified in his lack of faith that certain people in the FBI would either slow walk or actively hinder investigations, especially in view of the J6 persecutions and subsequent attempts to portray Trump as some sort of "insurrection" leader. A considerable amount of material had to be suppressed or ignored in order to paint Trump in the worst light and it was done out of political ideology, not a true and complete finding of fact.