You are trying to exclude file paths on DLP endpoint agents on Mac OS using environment variables, but notice that these are ignored
Environment variables are not currently supported for DLP agents running on MacOS
Release : 15.8 and earlier
Component : DLP Endpoint, Mac OS 10.x,11.x
Support for environment variables on Mac OS is anticipated in future versions of the product.
The current version of the Administators Guide does state that environment varibales are not supported on Mac OS, however this is under the section on Discover Scanning so this can appear to be restricted to only that function. It is however applicable to channel filters for other agent functions (copy to share, local drive, AFAC etc) as well.