Warning: SPOILERS for The Falcon and The Winter Soldier Episode 2, "The Star-Spangled Man"
Captain America: Civil War? The answer is yes. Sam Wilson/Falcon (Anthony Mackie) also called it a theft, and he reminded Bucky Barnes/Winter Soldier (Sebastian Stan) of what happened when Team Cap went rogue back in 2016.
After Steve Rogers received the Super-Soldier Serum back in 1945, he used a prop shield when he was given the identity of Captain America and sent on a USO stage tour to sell war bonds. When he went to Europe, Rogers used the prop shield in actual combat when he rescued the 107th Infantry Regiment, including Sgt. Avengers: Endgame's climactic battle.
But who really owns Captain America's shield" Rogers dropped the shield off with Stark and he didn't see it again for seven years when Tony gave the shield back to Steve during Avengers: Endgame.
Of course, the shield that's now in the possession of John Walker (Wyatt Russell), the new Captain America, isn't Steve Rogers' original shield anyway. At the end of Avengers: Endgame, Steve used the Quantum Realm to retrieve another shield from an alternate timeline, and he gifted that shield to Sam Wilson. So the shield that Sam and Bucky want back from John Walker is a substitute from somewhere in the Multiverse. However, as Sam said in his speech at the Smithsonian in The Falcon and The Winter Soldier's premiere, Cap's shield is more than a weapon - it's a powerful symbol of Steve Rogers' legacy as Captain America.
The Falcon and The Winter Soldier has further clarified that the shield is property of the U.S. Government, specifically the Department of Defense. Sam Wilson inadvertently reinforced this truth when he surrendered the shield to the Smithsonian's Captain America exhibit at the National Air & Space Museum. The government quickly repossessed the shield without Sam's knowledge. Indeed, the very identity of Captain America also belongs to the government, which chose John Walker to become the new Cap and carry the shield. The Falcon and The Winter Soldier is, in essence, about who is the rightful heir to Steve Rogers' legacy as Captain America – whether that's Sam Wilson or John Walker. But whoever does carry the shield as Captain America will also ultimately need the endorsement of its legal owners, the United States Government.