对一个网站发起多次请求，前两次正常返回html，后面返回的全是十六进制，怎么回事

import requests
basic_url = "https://search.51job.com/list/010000,000000,0000,01,9,99,+,2,1.html?lang=c&postchannel=0000&workyear=99&cotype=99°reefrom=99&jobterm=99&companysize=99&ord_field=0&dibiaoid=0&line=&welfare=%22
headers = {
"User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/99.0.4844.51 Safari/537.36 Edg/99.0.1150.36"}
r = requests.get(basic_url, headers=headers)
print(r.text)

下面是返回结果

网站做了cookie反爬措施。需要带上cookie请求。