For me it has nothing to do with companions, food, long resting, or vendors.
I was in the Zhent cave, saved, talked to the leader, fought all of them, tried to save and crashed.
Load it up, don't fight the zhents, just talk to the painter, tried to save and crashed.
Load it up, leave the Zhent cave, walk to the gobbo camp to sell, almost make it, pause to save just outside, crashed.
Load it up, leave the Zhent cave, walk to the druid grove (where I'd already been), tried to save and crashed.
In all cases my crash involves the creation of the C:\Users\******\AppData\Local\Larian Studios\Baldur's Gate 3\Temp directory, with a subdirectory that is the name of the save that only contains a .png in it, not an actual save. Make a new save? Does this. Try to overwrite an existing one? Does this, makes the directory under Temp.
What I think (I am not a coder) is that somehow the game has reached a point where it thinks it's "full" of saves (I deleted all of them but 1 so I could load) and is trying to write to an "overflow" area, because once it gets to this point it always does it. My current save game is 1 away from this crash, so no matter where I go or what I do, my next save crashes the game.
