Laplacian kernel for ksize=5?

The problem is simple. I want to replicate the laplacian filter for ksize=5 in c++ with a simple kernel and a convolution afterwards, but the output using a normal Laplacian Kernel of size 5 and the output given by the opencv function cv2.laplacian is different. It looks like the image returned by the OpenCV function has some kind of posprocessing. I tried to follow the steps in the c++ code but it is impossible to follow when ksize is not 1 or 3. Can someone tell me exactly what the laplacian function does please? Thank you

please show, what you tried (code, input/output images)