Little is known about the upcoming Black Widow movie, although every rumor we have heard points to the film being a story that pre-dates Avengers: Infinity War. That makes a lot of sense when you look at the way her character progressed following the events of that film and into Avengers: Endgame, but it raises some questions when fans have noticed her riding around in a 2017 BMW 5 Series Touring Wagon in set photos taken by amateur photographers and posted to social media. MCU Cosmic was the first to notice that the car was a 2017 model, and does not really fit into the previously-rumored timelines (either the '90s, the time around 2016's Captain America: Civil War, or a combination of the two).
You can see the photos in question below. With no official details yet available on Black Widow (technically it has not yet been officially announced, and our attempts to get studio head Kevin Feige to talk about it were a hilarious failure), anything could be possible. Certainly a 2017 car in the immediate fallout of 2016's Civil War, for instance, would not be too hard to swallow...although following the events of that film, Natasha (Scarlett Johansson) dyed her hair to be inconspicuous since she and other members of Captain America's team were considered fugitives from justice.
While one could be forgiven for assuming that there is a continuity or timeline error here, the simpler answer may be that portions of the film take place during the five-year gap between the death of Thanos at the start of Avengers: Endgame and that film's main story. The film could even be set at the time of the film's release, since the Avengers killed Thanos shortly after the events of Infinity War, and the five-year jump likely took the characters to 2023. Since the film is expected to be released in 2020, that means at least a framing device could take place during the gap between Thanos's death and (spoilers) Nat's own.
Avengers: Endgame is in theaters; Captain Marvel is new on home video this week. Spider-Man: Far From Home hits theaters on July 2nd. Beyond that, no Marvel films are officially scheduled yet, although fans expect to learn something during either Comic Con International in San Diego or perhaps Disney's own D23 Expo.