If you unblock a contact in WhatsApp, will they know - briefly?
If you unblock a contact in WhatsApp, they will not be notified of this action. However, they can potentially see your status updates and last seen information if these features are enabled on your account.
If you unblock a contact in WhatsApp, will they know - in detail?
When you block someone on WhatsApp, the app does not send them a notification that they have been blocked. However, there are some indicators that can suggest to the other person that their messages are not being delivered or read. For example, if you block someone, they will no longer see your profile picture, about section, or any changes made to them. Their sent messages will only show one checkmark (indicating it was sent), but no second checkmark (indicating it was delivered) or blue checks (indicating it was read).
When you unblock a contact on WhatsApp, the situation changes slightly. The person who was blocked will not receive any notification that they have been unblocked. However, if they try to send you a message after you have unblocked them, their messages will start showing the delivery and read status (the second checkmark and blue checks), which could indicate to them that something has changed.
Moreover, if the blocked contact tries to call you after you have unblocked them, the call will now go through, and they may notice that your profile picture and about section are visible again. This can also serve as an indication that they have been unblocked.
In summary, while there is no explicit notification sent to the other person when you unblock them on WhatsApp, changes in message status and visibility of your profile information can hint at the fact that they have been unblocked.