Per NIST [SP800-63B, §5.1.1.2] Memorized Secret Verifiers :
> the verifier SHOULD apply the Normalization Process for
> Stabilized Strings using either the NFKC or NFKD normalization
This is necessary for Unicode passwords to work reliably.
ASCII-only passwords aren't affected.
[SP800-63B, §5.1.1.2]: https://pages.nist.gov/800-63-3/sp800-63b.html#-5112-memorized-secret-verifiers