The industry has used “authz” and “authn” to disambiguate for decades.
Real travesty came from OAuth. A system designed to handle authorisation was named after the term for authentication.
I have always heard and used authz and authn (pronounced auth-z and auth-n). Bare "auth" typically was used to mean both, but IAM was more clear for that in specific contexts. E.G. you might say someone "authed" to indicate both authentication and authorization, and you might have an IAM team that handles both authentication and authorization.
FWIW, I lead an IAM team.
Maybe it's better to use less similar words if it's security related.
authn and authz are only clear if used as pair.