urllib3请求HTTPS接口跳转HTTP报无权限 同参数requests请求正常

我编写了如下使用urllib3发起请求的代码：

http = urllib3.PoolManager()
resp = http.request(
    "GET",
    "https://api.nhs.uk/medicines/aciclovir",
    headers={
        "subscription-key":"XXX"
    }
)
print(resp.data)

执行后得到的响应内容为：

You don't have permission to access "http://api.nhs.uk/medicines/aciclovir" on this server

我明确请求的是HTTPS协议地址，不清楚为何会被指向http://开头的地址。

但我使用requests库编写同参数的请求代码如下，却可以请求成功：

url = "https://api.nhs.uk/medicines/aciclovir"

payload={}
headers = {
  'subscription-key': 'XXX'
}

response = requests.request("GET", url, headers=headers, data=payload)

print(response.text)

现寻求该问题的产生原因及可行解决方案。

更新1 #

已确认执行的代码完全正确，确实返回了指向http://地址的无权限报错，相关运行截图见：

更新2 #

分别抓包获取两个库的请求头信息如下：

urllib3请求头 #

Listening on 0.0.0.0 7777
Connection received on *** 50054
GET / HTTP/1.1
Host: ***:7777
Accept-Encoding: identity
subscription-key: xxx
User-Agent: python-urllib3/1.26.9

requests请求头 #

Listening on 0.0.0.0 7777
Connection received on *** 50095
GET / HTTP/1.1
Host: ***:7777
User-Agent: python-requests/2.28.0
Accept-Encoding: gzip, deflate
Accept: */*
Connection: keep-alive
subscription-key: xxx

内容的提问来源于stack exchange，提问作者pee2pee