It is a texture pack, not an X-Ray mod (which removes blocks). You are only changing the render of light, not terrain. It is safe for survival gameplay.
: Players can see ores, dungeons, and lava pools from a distance, long before a torch would have illuminated them. How the Magic Works fullbright texture pack 1.12.2
While torches are the traditional solution, they clutter your inventory and only provide localized light. Enter the . It is a texture pack, not an X-Ray