Sorry for the late reply, Is this still an DeepStream issue to support? Thanks!
Please refer to this FAQ for python backend in DeepStream.
As the doc “To manage memory efficiency and keep clean interface, The Gst-nvinferserver Plugin’s default preprocessing cannot be disabled. Color conversion, datatype conversion, input scaling and object cropping are continue working in nvds_infer_server natively.” shown, if native normalization is not needed, you can update scale_factor to 1.0.