How to get rid of white vertical gridline(?) on tick marks on my area-type chart?

[aaron-mota]

I'm having issues with these white vertical gridlines(?) that chop up my area curve (so that it looks extremely segmented, instead of a nice and clean coloration/fill). I've tried looking in the docs and disabling gridlines and things, but I still can't seem to get them to go away. Anyone have an idea?

Photo of issue: (first screenshot)
Photo showing that the lines line up with my data points: (second screenshot)