user.identifier.deleted event is triggered when a user identifier is deleted.
An app's user's unique identifier. It is prefixed with 'usr_'
"usr_01jqebhswje1ka1z7ahr9rfsgt"
"usr_01jqy7455pf8p9bap5qke912g1"
"2025-03-15T10:30:00Z"
"corr_01jqy7455pf8p9bap5qke912g1"