I don\'t know why my plot looks like this:
I only want to display lines with no fill. Code below. Note this also happens if I run in Spyder or cmd.
This is an educated guess, since you don't provide your data (see Minimal, Complete, and Verifiable example), but I believe the shading comes from the fact that you have several y-values for the same x-value.
If you look at the documentation for sns.lineplot(), you'll read:
By default, the plot aggregates over multiple y values at each value of x and shows an estimate of the central tendency and a confidence interval for that estimate.
There are several options to remove the shading:
ci=None
estimator=None