Modified, or "modded" WhatsApp installs have existed for a long time. Some add innocuous features, such as a dark theme for those that want it, while others are more clandestine in nature, with a recent crop of WhatsApp mods allowing users to bypass the time limit they had before they could no longer delete sent messages. This allowed users of said WhatsApp mods to delete messages they"d sent as many as three years ago.
In its latest update on Android, WhatsApp beta gave us an extension to the said time limit, taking it from eight minutes to a little over an hour (1 hour, 8 minutes and 16 seconds, to be precise). Along with this update, however, in a bid to curb the practice of deleting three-year-old messages, WhatsApp has also debuted a feature called "Block revoke request".
When you make use of the "Delete for everyone" button for a certain message, a revoke request is sent to WhatsApp"s servers along with the message"s unique ID number. If the ID of your message matches the ID of the same message WhatsApp stores on their servers, the message is then deleted everywhere, which includes copies stored on the recipient"s phone. Just to be clear, WhatsApp stores only the message ID in its servers, and not the content of a message.
With this new feature, WhatsApp will now let these revoke requests work only if the message you want to delete was received (not sent, this is an important detail) less than 24 hours ago, rather than directly deleting it without any other checks, which was the case until now.
Its implementation is, however, a little flawed, currently. If the recipients" phone is unconnected to the internet through this 24-hour duration, WhatsApp"s servers would be unable to talk to the device, and the revoke request would ultimately be seen as invalid by it, leaving the message un-deleted.