Python 3 requests POST request data/params issue

The issue is that the data/parameters in the POST request aren't being sent correctly to be processed by the server. I've used Burp to check what's wrong and it seems like the parameters are in the request's body as they should, but the thing is that when I go to the params tab they don't show there, they're supposed to show there as body parameters, not URL nor cookie ones

Everything else works fine, if I edit the request and add them manually it works just fine. Although I would rather have the request headers being sent in the right order, but that's another question, I tried to use an OrderedDict to accomplish that but didn't work

Lastly, one of the parameters has a "+" in its value, it gets encoded like a URL would, in the original request that doesn't happen, so that needs fixing too

Any help would be appreciated, I've been trying for a while

Way of calling requests.post:

print(requests.Session().post(url=url, timeout=timeout, data=payloads, headers=headers, verify="C:\\OpenSSL-Win64\\bin\\certificate.pem").text)