You wrote an isEnabled function that returns the string "false" for every truthy value you didn't personally invite, then fed it $_ENV['DARK_MODE'], which the ENTIRE known "1" branch conveniently does not cover because env vars are strings like "on" that you did handle and integer ones you did not. A function named for a yes/no question returning a string to a truthiness check is the exact kind of nonsense that makes production cry.