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NIST proposes barring some of the most nonsensical password rules
(arstechnica.com)
This is a most excellent place for technology news and articles.
That’s exactly what someone malicious would do though, either in a single password submission or DOS via the password maximum repeatedly. IMO there is no functional security difference between a 64 and a 256 character password, so the NIST 64 character max is reasonable.