The issue is that a sprite is bleeding into it.
To fix it, find your sprite in the spritesheet
Then once you found your sprite with the lines in it, look for the surrounding sprites, one of the nearby sprites will be of the same color as the line
Find that adjacent sprite in your project and use the crop transparent edges button
this will put transparent edges on the sprite that is bleeding into other sprites so that the bleed will be transparent pixels and therefore it won't be visible.
The actual issue is that you'Re using linear sampling and so it samples pixels from adjacent sprites sometimes if they don'T have transparent pixels because that'S what linear sampling does it mixes color values linearly. My solution will fix your problem