Why is my PCA boomerang-shaped when normalizing?
The problem here is that you are normalizing the output of SVD. It might be clear that this output does not need to be normalized if you consider the output of each step:


Vectorizer: [n_items x n_words] Matrix. Unnormalized.
TFIDF: [n_items x n_words] Matrix with rows normalized to unit Euclidean norm.
SVD: [n_items x dim] Matrix. Columns correspond to each row's loading onto two orthonormal unit vectors.


In short, the output of the third step (SVD) is meaningful as-is and normalization obscures that meaning. 

As to why the normalized output appears curved? The math to show this seems a bit involved but my intuition is that normalization is mapping the row weightings onto the ellipsoid manifold used in SVD.