Почему ошибка? requests

from aiohttp.helpers import proxies_from_env
from bs4 import BeautifulSoup
import requests



proxies = {
  'http': 'http://136.243.211.104:80',
  'https': 'http://136.243.211.104:80',
}

def tbod(url):
 
    #with open("maiiin.html", "r", encoding="UTF-8") as f:
    #        req = f.read()

    
    req = requests.get(url, proxies=proxies)

    soup = BeautifulSoup(req.text, "lxml")
    a = []
    for i in range(0,30):
        link = soup.find_all(class_="text-center wd-100 pb-0")
        for i in link:
            for b in range(0,1):
                z = i.find("a")["href"]
                a.append(z)
        
    return list(set(a))



def check_stat(url):
    links = tbod(url)

    
    for i in links:
        url = "https://telemetr.me" + i 

        req = requests.get(url, proxies=proxies )

        #with open("index.html", "r", encoding="UTF-8") as f:
        #    req = f.read()

        soup = BeautifulSoup(req.text, "lxml")
        
        link = soup.find(class_="kt-widget__head").find("a")["href"]
        description = soup.find(class_="kt-widget__desc t_long").text
        subs = soup.find(class_="kt-number kt-font-brand").text
        description = description.replace(".", " ")
        images = soup.find(class_="kt-widget__media text-center kt-hidden-").find("img")
        image = images.get("src")
        link_img = link.replace("https://tmtr.me/joinchat/", "")
        channel_name = soup.find(class_="kt-widget__username").text

        with open(f"images/{link_img}.jpeg", "wb") as ph:
            ph.write(requests.get(image).content)
                

        return link, subs, description, link_img, channel_name



link, subs, description, link_img, channel_name = check_stat("https://telemetr.me/channels/cat/%D0%90%D0%BD%D0%B8%D0%BC%D0%B5/?page=1")

print(link,subs,description)

requests.exceptions.ProxyError: HTTPSConnectionPool(host='telemetr.me', port=443): Max retries exceeded with url: /channels/cat/%D0%90%D0%BD%D0%B8%D0%BC%D0%B5/?page=1 (Caused by ProxyError('Cannot connect to proxy.', OSError('Tunnel connection failed: 503 Service Temporarily Unavailable')))