Image Scraper (beautifulsoup), stopped working, need to help see why

[snippsat]

Try set User-Agent.
Here a quick test.

import requests
from bs4 import BeautifulSoup

url = 'https://archive.4plebs.org/hr/thread/2866456/'
headers = {'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/86.0.4240.75 Safari/537.36'}
response = requests.get(url, headers=headers)
soup = BeautifulSoup(response.content, 'lxml')
print(soup.find('title').text)
img_test = soup.select_one('div.thread_image_box > a > img')
print(img_test)
print(img_test.get('src'))

Output:
/hr/ - High Resolution » Thread #2866456
<img class="thread_image" data-md5="6SrRaBpXnbWSj3IZ9bTr+g==" height="176" loading="lazy" src="https://i.4pcdn.org/hr/1487896415236s.jpg" width="250"/>
https://i.4pcdn.org/hr/1487896415236s.jpg