"Aniara" is a spaceship, used to transport people (a LOT of people) from Earth to Mars. The movie starts on the ship, and we're told that Earth is in bad shape, but no further explanation is given. The ship starts on its voyage, and is shortly hit by a small piece of space junk - which completely disables their propulsion. They're left drifting, and a three week voyage suddenly becomes ... indefinite.
Wikipedia tells me that Aniara started life as an epic poem in 1956 (in Swedish, also the language of the film).
Our main view of the trouble is through the eyes of the ship's Mimarobe (Emelie Garbers) - she's the person who runs Mima, a system that allows visitors to experience the Earth as it was when it was healthy in immersive and completely convincing virtual reality. When the ship is suddenly left drifting, demand for the Mima jumps dramatically. They have enough food and water, but no significant hope of ever leaving the ship. No explanation is ever given of the situation on Earth, or why there's no external communication or assistance. I get that that wasn't the point of the movie (which was more of a horrible sociological experiment), but a few lines would have sufficed ...
I made connections to two other movies: "Wall-E" and "Passengers." There are significant differences in tone in both cases, but both involve huge passenger spaceships and unintentionally long journeys.
The movie is fairly good and makes you think about what would happen under those circumstances. But it's also brutally depressing, and not recommended viewing during a pandemic.