See https://github.com/w3c/web-platform-tests/pull/5121 (was also failing before that PR though).
Could you please provide a link for running the test too?
http://w3c-test.org/submissions/5121/cors/redirect-userinfo.htm until it lands (at which point drop "submissions/5121/" from the URL).
It seems this works in Safari TP 97.
*** This bug has been marked as a duplicate of bug 204036 ***