There is a controversial side to Fullbright. In PvP (Player vs. Player) scenarios, specifically on servers like Hypixel or 2b2t, fullbright offers a competitive advantage. It allows players to spot enemies in caves or at night without being encumbered by the limited radius of torches. It is often paired with "X-Ray" packs, though Fullbright alone does not make blocks transparent.
Unlike traditional texture packs that change the look of blocks, FullBright modifies the internal levels of the game.