Few can spot comparative power levels better than superhero fans. And Marvel Cinematic Universe's viewers have noticed something about Bucky Barnes' super-strength, particularly in light of his role in The Falcon and the Winter Soldier. As the titular assassin in Captain America: The Winter Soldier, he appeared all but invincible, able to dispatch multiple super-powered opponents with ease. That strength slowly diminished over his subsequent appearances, and while he's still strong, it pales in comparison to the level at which he began.
As a villain, it made sense to present the Winter Soldier as unstoppable, to make him a better foil for the heroes he fought. With his reformation comes an increased vulnerability; physically weakening him helps the audience better identify with him and ensures he can't simply knock out opponents with one punch. But the MCU also has implied a number of in-world reasons for the loss of strength, mostly tied to his slow emergence from Hydra's brainwashing. Indeed, the question of his lost power mainly comes down to a change in Bucky himself.
Bucky Barnes' Redemption Arc Softened His Strength
As the Winter Soldier, Bucky's combat abilities were enhanced at the expense of his humanity. He remained frozen in stasis for long periods of time, activated only when his masters had a mission for him. Logically, that reduced the amount of wear and tear his body suffered over time, giving him longer periods to recover from each mission by doing nothing and ensuring that he struck to kill every time. That meant holding nothing back and fighting all-out every time, which is reflected in his merciless assaults in Captain America: The Winter Soldier.
Once reformed, however, that equation became a lot more complicated. Bucky felt deep guilt and remorse over his actions as the Winter Soldier, and following his return from the Snap, he resolved to atone for his past. That can have a major impact in a fight. Pulling his punches in order to avoid lethally damaging his opponents means leaving them alive and fighting longer, which also means he has to take more punches from them in the process. Furthermore, in living his life, Bucky's been denied the downtime that came with years in the Cryostasis Chamber, forcing his body to recuperate naturally while going through events like those in Falcon and Winter Soldier. The combination is bound to have an impact as Bucky now fights with more care and has to pay the price for it.
Bucky Barnes' Fight Tactics Have Changed
Along those lines, Bucky makes far less use of firearms than he did as the Winter Soldier. He made an exception in Avengers: Infinity War and Endgame, but that was against aliens from Thanos' horde. In The Falcon and Winter Soldier, the weapon was gone, and Bucky relied almost entirely on his vibranium arm. He even made a point of not shooting Baron Zemo when he had a chance. That cuts down on his perceived power because fewer people are dying at his hands. But again, it's in keeping with his renunciation of his former self. No firearms mean fewer easy kills, and an attendant reduction in perceived power levels. Bucky clearly feels it's worth the cost.
Anything beyond that remains speculative, because Bucky's healing in Wakanda addressed his mental conditioning more than his physical skills. Indeed, Bucky's new vibranium arm is undoubtedly more powerful than his old one, because Wakandan technology is the most advanced on Earth. But Bucky's journey has led him away from the use of force. This detail is largely why his arc in The Falcon and the Winter Soldier focused on ways he could atone for who he once was. His apparently lessened powers are likely just a more judicious use of them, in keeping with his recovery and, perhaps, a desire to honor Steve Rogers' legacy in his own way.
Starring Anthony Mackie, Sebastian Stan, Emily VanCamp and Wyatt Russell, The Falcon and the Winter Soldier is available to stream on Disney+.