I am crashing on saves as well, right after talking to the painter after freeing him. I deleted all but a handful of saves, disabled auto saves, nothing seems to work.
One thing I've noted, normally my saves go into Local\Larian Studios\Baldur's Gate 3\PlayerProfiles\*******\Savegames, that's where the saved game I load is coming from. However, when I try to do this save, it creates Larian Studios\Baldur's Gate 3\Temp and puts the save there. I watched it happen, deleted that Temp directory, loaded the game, tried to make a save (new save or over-write, it didn't matter), it creates Temp, creates the save directory, shoves a .png in there but no .lsv, and then crashes to desktop.
Do we think my profile is corrupted?