The URL parsing in httpx is rfc3986, which is not the same as WHATWG URL living standard. rfc3986 may reject URLs which browsers accept, or it can handle them

The URL parsing in httpx is rfc3986, which is not the same as WHATWG URL living standard. rfc3986 may reject URLs which browsers accept, or it can handle them in a different way. WHATWG URL living standard tries to put on paper the real browser behavior, so it's a much better standard if you need to parse URLs extracted from real-world web pages.