When I upload my logo png file to the theme it puts a white outline around the image. I have uploaded the image in different places on the theme and it does not have the white outline. It only has the white outline when the image is uploaded in the logo section
With the background dark your logo display some white area but it’s not outline.
It come from your logo. You need delete it in your logo.
Maybe you use eraser tool of Photoshop and it cause this issue.