Question: How to smooth piecewise graph edges?

I have been working some plots using piecewise, and this seem to always result in graphs with very jagged edges

Example: https://i.imgur.com/ZBOSDsL.png

The function its plotting is this one:

f:=unapply(piecewise(x^2+y^2 <= 1 and x>=0, 4*x*y^2-x^2, undefined),x,y):

Now I assume this happens because of the piecewise part. How do I smoothen the edges?

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