Have the latest version of .NET via Windows 11 on my computer, Early Access was NO issue. Now I'm getting an error saying .NET isn't installed! Ridiculous. Screenshot attached. Clicking on "Yes" doesn't even do anything, and when I go to the official .NET website, it says I already have .NET installed.

Update: downloaded the preview 8.0 .NET to try and make it work, but still isn't.

Final update for now: ran the DX exe in the bin folder which I read about in another thread from a year ago. Then launched the bg3 exe rather than "Play Baldur's Gate" and it works. Probably won't get acknowledged in GOG but am hoping this gets resolved sooner than later.

Should come from the Launcher which needs .NET. One thing you can try is to get over the Launcher. You have to search how to do that in Windows.
In Linux I just set the variable --no-launcher. But I can't say, if this helped with my own .NET error.

I was able to get in using bg3 but the graphics are completely fucked up following the character customization screen.

Try the dx11 version.

I also had the .Net Error and for me checking the game installation and re-downloading some corrupted files worked. (Did take some time though)

Did this work in the end? I'm running it on the Deck and I'm looking at a lot of missing shaders as well.
This occurs regardless of which EXE I run.

https://www.gog.com/forum/baldurs_gate_3/steam_deck_black_artefacts_missing_shaders/post1