The Biden documents

Looks like the National Archives were complicit in keeping their discovery secret.
From the London Daily Mail:

What ELSE are they hiding? White House claims of transparency face even more scrutiny as it's revealed National Archives was BLOCKED from releasing statement on classified documents found at Biden's think tank
The National Archives was prevented from notifying the public that classified documents had been found at President Joe Biden's think tank back in November, raising questions over who stopped the information from coming out.

House Oversight and Reform Committee Chairman James Comer raised the question Tuesday night, claiming the only two entities that could have given the order are the White House and the Department of Justice – putting the onus on either Biden or Attorney General Merrick Garland.

Despite Biden's team claiming they have been 'transparent' regarding the classified document scandal, new details emerged Tuesday that the FBI had searched his former offices after the initial materials were found.

Documents with classified markings were found at Biden's Washington, D.C. think tank in early November, just days before the 2022 midterm elections.

As a reminder, President Trump fully cooperated with the National Archives regarding the documents he took.  They had been declassified.  Remember that the President has that authority - the Vice-President does not and Biden was VP at the time he removed the documents.

The mid-term elections were a few days away at the time they were "discovered" - they kept a lid on it so as not to disadvantage any Democrats.

As a reminder, these were not just a file folder or two - this was a major haul: