As an update and to complement Alex's answer, this option is not working properly using seaborn

sns.scatterplot(
    data=tips,
    x="total_bill",
    y="tip",
    c=kernel,
    cmap="viridis",
    ax=ax,
)

Use instead:

  plt.scatter(tips["total_bill"], tips["tip"], c=kernel, cmap='viridis')