Constant POD_NAMESPACE_ENV 

pub const POD_NAMESPACE_ENV: &str = "POD_NAMESPACE";

Downward-API environment variable carrying the operator pod’s namespace.

src/bind9_resources.rs reads this to compose the BIND_ALLOWED_SERVICE_ACCOUNTS value for operand bindcar sidecars; without it the operator falls back to bindy-system and bindcar rejects tokens from operators installed in any other namespace.