Isn't "authorized designee" redundant?
Authorized implies a formal relationship that is not casually reversed:
Definition of authorized
1 : endowed with authority
an authorized representative
2 : sanctioned by authority : having or done with legal or official approval
an authorized biography
an authorized translation
https://www.merriam-webster.com/dictionary/authorized
The term designee does not in itself suggest an official or legal or demonstrable delegation of decision-making responsibility, and thus the adjective “authorized” is not obviously redundant.
As @WeatherVane says in a comment: “ Authorized" means that the appointment has followed the rules and procedures laid down in a constitution or code of practice, and perhaps given in writing, rather than an informal "you can represent us." Suppose a contract is signed: the signatory must be legally authorized to sign the document for it to be valid.”