Verification_code email is always sent from root@auth0.com and fails

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verification_code for passwordless flow emails are always sent from root@auth0.com, even with custom domain and email providers set. that result with errors like this one

details": {
    "email_type": "verification_code",
    "to": "xxx@gmail.com",
    "error": "Error sending email: Message failed: 554 Message rejected: Email address is not verified. The following identities failed the check in region XXX-1: Your APP <root@auth0.com>, root@auth0.com"
  },

other templates (those which have try button) are send from the correct custom email. how to force this one to work as intended?