Drugs in the White House is not abnormal. Mary Todd Lincoln presumably left laudanum all over the place. William Henry Harrison’s doctor used Dover’s powder (ipecac plus opium) on the president during his 31 brief days in office. And of course, Thomas Jefferson literally grew opium poppies at Monticello. Reports say that George Washington used laudanum, which was an opiate derivative. Some associates of John F. Kennedy say that he used LSD and marijuana.
There are 524 staff members in the Biden White House, as of July 1, 2023, so the cocaine could belong to anyone.