They aren't pixelated anywhere unless you have graphics quality set below "normal" (which you seem to have it on high so that's fine).

You're zooming in more than the native resolution which means the image gets scaled up. If you press F9 it will zoom to the default size and you can see they will ...

When I first found out about the Sprite Atlas I was shocked to see the textures are not pixelated by default but pixelated in post. I really would love to use the raw textures because they look absolutely gorgeous, even with the highest graphics settings I couldn't reach this. I reckon this was done ...