Most servers allow Fullbright because it only changes how you see things, not the actual light levels (mobs still spawn in the dark). However, always check the server rules as some may consider it an unfair advantage. other 1.12.2 mods
Finding a reliable that doesn't require OptiFine can be a bit of a challenge. While OptiFine is the go-to for most players, many prefer a "vanilla-plus" experience or are running specific modpacks where OptiFine causes compatibility issues. What is a Fullbright Texture Pack? fullbright texture pack 1.12.2 no optifine
Contrary to popular belief, a texture pack (or resource pack) cannot normally change how light levels work. Light is calculated by the game engine, not by textures. Most servers allow Fullbright because it only changes