https://faq.whatsapp.com/5957850900902049

Unauthorized use of automated or bulk messaging on WhatsApp

https://faq.whatsapp.com/508673377786103

Seeing the message "Your phone number is banned from using WhatsApp. Contact support for help."

https://www.whatsapp.com/legal/terms-of-service

Legal And Acceptable Use

(e) involve sending illegal or impermissible communications such as bulk messaging, auto-messaging, auto-dialing

https://www.whatsapp.com/legal/business-terms/

Restrictions

(h) create software or APIs that function substantially the same as our Business Services and offer them for use by third parties in an unauthorized manner on or utilizing the WhatsApp platform or our Business Services.