Whether or not the documents were declassified or not is irrelevant. Trump is being charged with the Espionage Act and that says nothing about classification. It deal with National Defense Information which can be classified or not. The Espionage Act has never been applied to a President or ex President and frankly cannot apply to them since in both roles they retain authorization to access National Defense Information.
We also know that prior to the Presidential Records Act implementation in 1981, earlier Presidents retained possession of White House records that included National Defense Information, Roosevelt and Eisenhower both had such materials at their private offices until later moved to either private or Presidential libraries. I have not researched it but would not be surprised if Truman, Johnson, Wilson, Harding, Coolidge and Hoover also retained NDI as part of their Preside trial records. None of them was ever charged with the Espionage Act and that clearly infers that ex President’s were not covered under that law.
This is an Article II case and that’s all it is.
The blowback from killing JFK put pressure on the CIA to find another way to eliminate a President who could eliminate them. Hence the “independent counsel” invention from Nixon’s DOJ, the idea that there are, or even could be, officers appointed by the President - you know, as in “Executive power is vested in a President of the United States” that are not subject to his commands - an obvious absurdity.
The gaslighting around “Watergate” has had such a strong effect that entire government departments rallied to eliminate the duly elected 45th President without having to blow his brains out and cover it up.
And that’s where we are.