ENABLE_AR compiler define persisting in other platforms

So in building our game on iOS with ARKit support, we have the ENABLE_AR symbol defined in Player Settings -> Other Settings -> Scripting Define Symbols. Specifically, we have the following defined:

Code (CSharp):

1. CROSS_PLATFORM_INPUT;MOBILE_INPUT;ENABLE_AR

For our standalone build, we have fewer symbols:

Code (CSharp):

1. CROSS_PLATFORM_INPUT

However, when I try to build for PC, the following code is still being executed:

Code (CSharp):

1. #if ENABLE_AR
2. print("This should not print in Standalone builds.");
3. #endif

Is there something in the ARKit plugin that is defining ENABLE_AR before every build, regardless of platform? Is it affecting a list of globally-defined scripting symbols? Why does this code execute on a PC build?