I found a doj doc that says prosecutors often move the courts for 6 month extensions in sealed whistleblower cases
sauce:
https://www.justice.gov/sites/default/files/usao-edpa/legacy/2012/06/13/InternetWhistleblower%20update.pdf
…" the Department of Justice must, if it wants the
case to remain under seal, file a motion with the District judge showing “good cause” why the
case should remain under seal. In the usual course, these motions request an extension of the
seal for six months at a time. "