Baldur’s Gate 3 is a story-rich, party-based RPG set in the universe of Dungeons & Dragons, where your choices shape a tale of fellowship and betrayal, survival and sacrifice, and the lure of absolute power. (Website)
If your post contains any possible spoilers, please:
Thank you!
spoiler
Unfortunately you don't really get to witness the shadow curse lifting, at least not in any way that provides content, gameplay, or exploration.
The most you get is a cutscene when transitioning from the end of Act 2, to the beginning of Act 3.
On an unrelated note. You can't return to Act 1 or Act 2 locations once you begin Act 3. Make sure you head to the mountains and do the content there before you leave.
Yeah one of the things I was quite disappointed about was that I couldn't go through that zone and see it restored because I think it would have been so beautiful.
That would mean they would have needed to remake all the zone for virtually nothing since it's not like you would do anything in there.
When it actually goes away, you won't be able to come back and take a good look. There's a cut scene that shows it all getting better as you leave for Baldur's Gate.