I have a theory:
The FISA DECLAS wasn't meant to go public right away. They can't release anything being used in an ongoing investigation. Trump declassified the FISA app so it can be presented to the grand jury
>Congress provided the demand to DECLAS
>Trump agrees with Congress
>Trump gives it to Horowitz to "review"
>Horowitz gives it to his dedicated prosecutor Huber
>Huber drops it to the GJ
>BOOM