In the latest updates for iOS and Android, WhatsApp made slight changes to notifications related to blocking and unblocking contacts.
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In case of blocking someone, WhatsApp notifies you in the chat with a notice that also gives you the option to unlock contact. This notice does not appear to the user who was blocked, although he can give an idea through other avenues.
If you try to contact a user that you have blocked, but let’s say you had already forgotten, WhatsApp also notifies you with this same notice, and gives you the option to unblock it.
Obviously, WhatsApp will notify you with another notification that says “You have unlocked this contact.” This notification will also not appear to the user unlocked from their mobile.
The messaging application also implemented a small improvement to the list of blocked contacts, by separating the blocked contacts that were made by an individual from those that were made by a company.