I'm pretty sure the look at does exactly what you described, from the docs, it looks at a Vector3 coordinates in space there is no rotation included in the description or parameters.
On the other hand, what you describe seems to be that your camera is a child of your
RigidBody, like most tutorials show because that makes following really easy, basically free. But that also means that the Camera itself is being moved and rotated in accordance to it's parent, a child node local space is based on the parent, so when the
RigidBody moves and that includes the body rotation the camera moves and rotates with.
As such, you should think about making the camera a sibling of the RigidBody and move it in accordance to the RigidBody transform minus rotation. Or clean up the parent rotation every frame from the camera base.