At the end of Captain America: Civil War, Steve Rogers' dispute with Tony Stark led him to drop his red, white and blue shield. As a result, Steve effectively dropped the Captain America mantle and went on the run from the government after freeing his friends from the super-prison known as the Raft. And this couldn't have happened at a worse time because Thanos was coming to Earth very, very soon.
Steve would next return in Avengers: Infinity War, where he first appeared fighting alongside Black Widow and Falcon as part of the Secret Avengers. But unlike other new installments in the Marvel Cinematic Universe, Steve didn't return to the big screen with a fancy new costume. No, this time, he was wearing a dingy, darkened and torn version of his Captain America suit.
Throughout the MCU films, Captain America's costume changes have always been story-driven and symbolic. His first, brightly colored costume came when he joined the Avengers; he returned to his World War II costume to take on a resurgent Hydra; and he put on a new, Tony Stark-designed suit to fight alongside Earth's Mightiest Heroes against Ultron. And the case is the same for the character's costume in Infinity War.
The dark costume Steve wears as part of the Secret Avengers is the one the character wore throughout Civil War. After going on the run from the authorities at the end of the film, Steve didn't have any funding from Stark or access to any kind of gear. Therefore, he was stuck with what he already had at the end of Civil War -- and that wasn't much to begin with. The lack of the white star and the fading of the white coloring is what helps make this costume darker, and it clearly shows that it has been torn, scraped and dirtied during other missions. After all, it was confirmed in the commentary track of Infinity War that Steve, Natasha and Sam form the MCU's version of the Secret Avengers, which indicates the three superheroes have still been active in the dark.
On top of that, the costume is also symbolic in nature because it shows that Steve is no longer Captain America. Without his star and stripes, he is just a super-soldier in a dark costume. Before the release of Infinity War, there was a theory that this was the MCU version of Steve Rogers' Nomad suit. In the comics, the superhero stopped being the Sentinel of Liberty and took on the mantle of Nomad in 1974's Captain America #180. His new costume was primarily dark blue, and it was infamous for featuring a deep neckline as well as a yellow cape -- something Steve isn't exactly known to be wearing.
Given that, in the MCU and in the comics, Steve Rogers stopped being Captain America and wore a dark blue costume, it surely seems like Infinity War gave fans its own twist on the Nomad uniform. After all, for the past two years, Steve was living on the run, moving from hotel to hotel, as Falcon reveals. Therefore, Steve, as well as the other Secret Avengers, really were nomads.
Directed by Joe and Anthony Russo, Avengers: Infinity War stars Robert Downey Jr., Chris Evans, Chris Hemsworth, Mark Ruffalo, Jeremy Renner and Scarlett Johansson with Paul Bettany, Anthony Mackie, Paul Rudd, Elizabeth Olsen, Tom Holland, Benedict Cumberbatch, Chadwick Boseman, Chris Pratt, Zoe Saldana, Dave Bautista, Bradley Cooper, Vin Diesel, Tom Hiddleston and Josh Brolin. The film is currently available on Digital HD, Blu-ray, 4K UHD and streaming.