https://www.techdirt.com/articles/20210926/10082447632/there-may-be-new-boss-doj-government-still-loves-indefinite-gag-orders.shtml

Despite the DOJ recently drawing heat for its targeting of journalists during internal leak investigations, a lot still hasn't changed about the way demands for data are handled by the feds. Over the past couple of decades, the DOJ and its components have been asking for and obtaining data from service providers, utilizing subpoenas and National Security Letters that come with indefinite gag orders attached.

These orders swear recipients like Microsoft and Google to secrecy, forbidding them from notifying targeted customers and users. (Even Techdirt has been hit with one.) Unlike regular search warrants, where the target is made aware of the rummaging by the physical presence of law enforcement officers, warrants, subpoenas, and NSLs allow the government to go about its rummaging unnoticed.