1. There was an update, Patch 2, about 4 days ago. The news was all over the gaming part of the net.
2. Reinstalling Windows was stupid.
3. Reinstalling the game equally so.
4. That you were baffled is evident from your post.
5. Did you send the error report to Larian?
6. Did you think to use a search engine?
7. Did you think to read any of the many posts on this forum making similar complaints?
8. You have just learned the valuable lesson that having things update automatically is not such a good idea after all.
Option 1:
Go to your Baldur's Gate 3\Data folder and remove (do not delete) Patch2.pak and see if your game works
Option2: Try launching the game directly from the exe. If you are using Vulkan the exe is Baldur's Gate 3\bin\bg3.exe if you are using DX11 the exe is Baldur's Gate 3\bin\bg3_dx11.exe
Create a desktop shortcut for each exe and try loading the game from both.
