This is amazingly amateurish behavior on the part of Trump's handpicked inexperienced prosecutor. Going off the record with a journalist is something the journalist has to agree to, and if they don't agree to it, you're still on record. And you definitely don't get to just declare it retroactively! This is incredibly basic stuff for anyone dealing with the press.
“Anna, Lindsey Halligan Here.”
My Signal exchange with the interim U.S. attorney about the Letitia James grand jury.
lawfaremedia.org