[ceejayoz]

It's entirely likely some of the remaining JFK files - a big batch got released under Trump, and another under Biden - are victims of over-classification. It's a systemic problem in the government.

It's also fairly likely some of the remaining classified docs include "we asked our mole at the Russian embassy to check into it discreetly" and "spy satellites checked to see if Russia was quietly mobilizing in advance" sort of scenarios likely to remain indefinitely secret.

[MichaelCollins]

It's also possible that some of the JFK files might implicate an influential American ally, with whom JFK had a dispute concerning their nuclear weapons program.