I bet the document was disappeared.
Use of the word ‘unclassified’ leads me to believe the whistleblower may have legally made a copy of said document and has it placed in the Senate/House GOP investigators’ possession.
Correction. Make that:
"We believe that the FBI used to have a heavily-redacted, formerly-unclassified internal document that has, unfortunately ingested by a hungry dog mistaking it for a homework assignment.
We'd really like to see it, but don't waste too much time looking around, especially since it's been recently marked REALLY, REALLY TOP SECRET. We know you're awfully busy rounding up J6ers and White Supremacists."
(With apologies to Jim Jordan and a couple of others who are truly trying get something done. Unfortunately, it's basically hopeless.)