On my ex-US flight, I heard another pax ask about the lack of PDB and the explanation given was something about how duty had already been paid on the alcohol so they weren't allowed to open any of it until after takeoff, for fear of a tax fiasco if the flight was unable to depart for some reason. Sounded like a lot of bologna, which I thought was weird when they could have just said that they haven't brought back PDBs after COVID yet.