You could possibly try turning on pixel snapping, and snap to the center of the pixel, since that vertex is interpolating the corner between many different textures.
This is pixel padding. It is a good thing. It makes it so when your texture gets mip-mapped in game (sized down) the data doesn't bleed over the edges and cause seams. If anything, you should have even more pixel padding (too much pixel padding isn't a thing) I set pixel padding to 96 pixels in xnormal. Apply the texture…
Pixels are square by default. And they are interpolated to make them appear smooth. Now imagine laying your uvmap on the square pixels. If you don't pixel snap the border of the uv islands, they will hang over to empty pixels. Dilation expands the uv borders and fill the neighbouring pixels with with the original color.…