Another thing that bothers me about BG3. We have extremely vertical locations. And yes highground gives advantage. Yet flying creatures don't fly, AoE like cones and cubes are flat. So you can't direct them up or down. I had an unpleasant situation when fighting on a hill. Burning hands got cut off in the middle of the cone becouse of height change (and spell was directed downhill). That could be a bug since it is very inconsistent.
I'm afraid about how Larian are going to implement spels like "Fly" and "Levitate".
I surely hope this is just another part of the game that is not in its final state due to early access.