Here is a part that applies to some of the notes from each Biden and Trump, but does not in any way apply to the documents that Biden had. It also is an example of how Barr was quite full of it:
The clearest example is President Reagan, who left the White House in 1989 with eight years’ worth of handwritten diaries, which he appears to have kept at his California home even though they contained Top Secret information. During criminal litigation involving a former Reagan administration official in 1989 and 1990, the Department of Justice stated in public court filings that the “currently classified” diaries were Mr. Reagan’s “personal records.” Yet we know of no steps the Department or other agencies took to investigate Mr. Reagan for mishandling classified information or to retrieve or secure his diaries.