I checked the opencv library version in python it is the correct version, I don't have any other version of opencv installed. I even tried on a fresh installation of wsl Ubuntu 20.04 just to make sure ...

OpenCV on Wheels Pre-built CPU-only OpenCV packages for Python. Check the manual build section if you wish to compile the bindings from source to enable additional modules such as CUDA.

Today Nvidia announced that growing ranks of Python users can now take full advantage of GPU acceleration for HPC and Big Data analytics applications by using the CUDA parallel programming model.