This has been in their guidance since at least 2017.
"Verifiers SHOULD NOT impose other composition rules (e.g., requiring mixtures of different character types or prohibiting consecutively repeated characters) for memorized secrets. Verifiers SHOULD NOT require memorized secrets to be changed arbitrarily (e.g., periodically). However, verifiers SHALL force a change if there is evidence of compromise of the authenticator"
Also worth pointing out that NIST doesn't set policy, so unfortunately this doesn't directly "forbid" anything, though many other policies reference 800-63.
The factors are:
- Something you know
- Something you have
- Something you are (biometrics)