If you're going to start talking about rules and alignment, you're wrong on both counts. Forgotten Realms has had both good/neutral vampire spawn (Jander Sunstar), and priests of evil gods can be neutral so long as their alignment is no more than one step away from their god.
I'm talking about both FR lore and rules. Jander Sunstar was created as a character to precisely be an exception to the rules. And FR lore is very clear about the kind of control Shar exerts over her clergy. So the only way you could argue this is to claim that all of the BG3 companions are *special* exceptions to FR lore and rules. And if that is the case, then we would have a whole other huge complaint about the game.
