How to increase the quality of violinplot

Hi, anyone can help me to make the outlines of the violinplot look smooth? I’ve played around with the options, but it seems like the anti-aliasing for the outlines is off. It helps when there are fewer violins. Thanks for any help in advance.

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I have set outline_alpha=0 to achieve a slightly pleasant outcome. But I would still be grateful if someone can help me understand why the outlines look zigzagged.

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