Why my python requests are failling with a 503 status using PRIVOXY and TOR?

Question

Im trying to use Privoxy and Tor to rotate my IP address in order to scrape a site without getting ban by IP.

So I installed Tor with sudo apt intall tor and then modified the /etc/tor/torrc file enabling these lines:

SocksPort 9050
ControlPort 9051
HashedControlPassword 16:A...
CookieAuthentication 1

Same for Privoxy sudo apt install privoxy and then sudo vim /etc/privoxy/configwhere I added forward-socks5 / 127.0.0.1:9050 .

Then, following this article, I created a rotate.py file which will be rotating my IP address every certain minutes. It looks like this:

import time
from stem import Signal
from stem.control import Controller
def main():
    while True:
        time.sleep(60*10)
        print ("Rotating IP")
        with Controller.from_port(port = 9051) as controller:
          controller.authenticate(password='mylovelypassword')
          controller.signal(Signal.NEWNYM)
if __name__ == '__main__':
    main()

On the other hand, Im performing a python POST request to get the data that I need and it looks like this:

final_cookie = get_cookies()

url_base = 'http://...'

url_string = '...'

headers = {
...

    "User-Agent": """Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.141 Safari/537.36"""
}

proxies = {"http": "127.0.0.1:8118"}

data = requests.post(url_base, headers=headers, data=url_string, verify=False, proxies=proxies)

So I first run the rotate.py script and then I run my scraper that will be performing those POST requests. The issue is that Im getting status code: 503 everytime. If I just do a normal request like data = requests.post(url_base, headers=headers, data=url_string, verify=False) it will actually get the data (200 response), but it will get blocked after a certain amount of requests.

So what could be causing that my Privoxy-Tor setup is just getting 503 error reponses? Is it something with the services configuration? Any advice/hint will be very appreciated by me :) Cheers!!