This OpenVINO version check is necessary to avoid compilation errors in older versions.
For older OV versions I get this error: C2039: 'qdq_optimization': is not a member of 'ov::intel_npu'

The reason for this behavior:
This check happens at runtime, because it queries the device's supported properties dynamically.
if (std::find(supported_properties.begin(), supported_properties.end(), "NPU_QDQ_OPTIMIZATION") != supported_properties.end())

However, the line
OVCore::Get()->core.set_property("NPU", {ov::intel_npu::qdq_optimization(true)});
happens at compile-time, since the compiler needs to resolve qdq_optimization(true) during compilation.

If ov::intel_npu::qdq_optimization(true) does not exist in an older OpenVINO version, the compiler treats it as an undefined symbol and throws an error before execution—long before the std::find(...) check can even run.

#if preprocessor checks ensures that qdq_optimization(true) is only compiled when the OpenVINO version supports it, preventing compilation failures in older versions.