When you send outgoing messages through the WhatsApp channel, there is no way to identify which users have blocked your company's number from receiving your notifications, since WhatsApp does not make this information available, protecting the entire user experience.
Considering this:
It is not feasible to identify how many of the messages you sent and were not actually delivered are from users who blocked the number;
It is also not possible to identify the WhatsApp numbers of the users who blocked the number so as not to send them more campaigns.
This is why it is very important that you can incorporate the use of the Opt in and Opt Out policies required by WhatsApp.
Update 17/8/2022