This would be such an amazing premise for a scifi movie. One such planet drifts through the solar system, and we have like 3-5 years to make contact with whatever lives there before it drifts away.
The premise is that humans turned the Earth into a planet-scale space vessel to escape the sun's expansion and rehome into a different solar system. Basically involved de-orbiting the Earth and coming up with a way to fling it out of the solar system whatnot.
The sci-fi parts are quite interesting, though I'd recommend the book instead of the movie (which is really a mediocre Chinese take on the Hollywood blockbuster...)
I quite enjoyed the film. It was interesting to see a different cultural take on how to solve "future problems" in a different cultural SciFi. Would I watch it again? Probably not, was it any worse than the stream of MCU junk? Not really.
Exactly. Hence the "mediocre". It's a familiar storytelling format with a different set of ideological undertones. Nothing special but also not like it's bad or anything.
OTOH, Liu Cixin writes what I would call pretty good sci-fi novels and shorts which the movie doesn't do enough justice to. Then again that's more or less most sci-fi movies compared to their original works.