I tried the regex101 link, it extracts the domain field at the very end. That field is not always populated So I tried to extract the domain from the string right after "DIRECT/". This would be my solution. But only if you are not looking at the field at the end.
(GET|POST)\s(?<url>[^ ]*)\s(?<user>[^ ]*)\s([^ ]){6}\/(?<domain>[^ ]*)
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