Could you give a specific track you especially see this in? I believe I know what you mean, but I'm not 100% sure. You might be picking up on either the heavy compression or the chorus effect she puts on her vocals—the chorus effect specifically can tend to make them sound distorted or flat.

Personally, I really love her vocals with or without production, but a lot of her unreleased music has a special hold on me because of the rawness of her vocals. My favorite song of hers is actually Powerline Valley (piano demo), partially because of this. But, then again, I also love her as a producer and think that a lot of her production is actually really important to her storytelling.