Thunderbolts includes many returning MCU characters, and it's the perfect opportunity to answer an unresolved 3-year-old question. Marvel's Thunderbolts is essentially its version of DC's Suicide Squad. It features several antiheroes coming together for a dangerous mission that falls outside the Avenger's purview. The roster includes Yelena Belova, Red Guardian, Ghost, U.S. Agent, Winter Soldier, and Taskmaster. All these characters are brought together by Valentina Allegra de Fontaine, who appeared in The Falcon and the Winter Soldier and Black Panther: Wakanda Forever.

https://screenrant.com/thunderbolts-movie-black-widow-unanswered-mcu-question/