He is charged with violation of the much older Espionage Act. The Espionage act (origin in WW1) predates the modern classificaion scheme (origin WW2) and the laws that enforce it.
BECAUSE: Everything you say (and others have said) is TRUE: Trump did have the right to declassify thing, as he saw fit, without a requirement to follow any particular process, the STATE is not claiming he broke any "Classified Documents" law.
They are claiming he broke the Espionage Act by providing (or not protecting) material potentially beneficial to an enemy.
You can read the indictment yourself to verify this. Most people (including apparently most MSM reporters) don't bother to do that. (Lazy jerks).
Thanks for that clarification. The selectivity of prosecution is as strong with the use of the Espionage Act as it would have been, had the indictment been about keeping classified documents. After all, lest we forget, Biden kept sensitive defense related documents in his freaking garage and at various other non-secure locations around town.
Thanks for the reminder.