As a Roblox developer, it is currently confusing that Lua preprocessors are at all referenced in Roblox. There is currently a setting under Studio that is called Preprocessor Color. This property does nothing.
Once upon a time, Lua had preprocessors. They were removed in Lua 4.0. Roblox uses Lua 5.1. Preprocessors should never have been referenced in Roblox Studio, and that they are at the moment should be corrected.
If the Preprocessor Color setting of Studio was hidden (scripts may be setting it so straight up removing it would probably be bad), it would remove a source of lasting confusion from Studio’s settings.