What could cause those lines and blurry patches in Antarctica images?

If it is a map or satellite mosaic, the lines may be joins between separate image captures. A sudden change in sharpness, color, or texture along a straight boundary points more toward processing than a track. The blur could come from cloud cover, lower-resolution data, or an area obscured in the source imagery. Without the exact image, those are possibilities, not a diagnosis.

First check the shape. A line that follows the terrain or bends naturally could be a surface feature or a vehicle route. A very straight stripe, repeated striping, or a line that cuts across unrelated features is more suspicious as an imaging artifact. A shadow or an aircraft contrail is possible too, depending on the image and its date.

Try opening the same spot at another zoom level or comparing imagery from a different date. Map views can combine captures with different resolutions or capture conditions, so a blur or seam may shift or disappear. The image source and capture date would help narrow it down.