The Dispossessed (Anarcho-Communist lunar colony re establishes contact with the rest of the world after 100yrs due to making a huge scientific breakthru) or any other Ursula le guin novel.

xenogenesis series by octavia e. butler. Humans wiped themselves out, horny aliens offer a deal, they restore earth and in exchange humanity interbreeds and merges with the aliens.

House of the scorpion king: drug lords have annexed Mexico and collapsed the us, the king pins live forever using clones for organ harvesting and have a mentally stunted slave class to do the farming. It's a very heartwarming story in my opinion.

Project Hail Mary, by Andy weir who wrote the Martian (also good book). It's hard to describe the book without spoiling it, but essentially slightly more advanced society than ours pools the whole worlds resources to send the protagonist on a one way interstellar mission to discover a way to save earth.

I also just finished the three body problem series, I enjoyed the second book in particular, its beautifully written and well translated but I felt like the series is severely hurt by the authors sexist themes.