When Sam, Bucky, Zemo, and Sharon find Dr. Nagel in Madripoor, he reveals that his super-soldier serum was only successful because of the blood samples taken from Isaiah Bradley when he was wrongfully imprisoned. He also reveals that he vanished in the Snap midway through his work on the serum, which means that the U.S. government was performing super-soldier experiments as recently as Avengers: Infinity War. That’s not a shocking development, but it does beg the question – who was behind the recent experiments, and how didn’t any of the Avengers know about them?
One explanation is that, after the events of Civil War, the U.S. decided to create new superheroes to replace the ones they’d lost. Captain America going rogue was obviously undesirable for the Pentagon, so it would make sense that someone somewhere decided to create more loyal super-soldiers. However, it doesn’t quite make sense that characters like Nick Fury, Black Widow, and War Machine had no idea the experiments were going on – unless, of course, they were extremely covert. Since super-soldiers count as sentient weapons, it’s possible that the U.S.’s experiments could have been connected in part to SWORD, not to mention illegal under the Sokovia Accords, tying the events of The Falcon and the Winter Soldier to those of WandaVision.
Originally from https://screenrant.com/falcon-winter-soldier-episode-3-unanswered-questions/