Unity editor scripts for preprocessing CC0 Textures
The normal map format used in CC0 Textures is different from the standard normal map format in Unity. If you use it without a fix, it will end up giving wrong bump directions.
(left: original normal map, right: fixed normal map)
To fix the normal map format, select textures in the project view, then select "CC0 Textures" -> "Fix Normal Map" from the right-click menu.