As per the report, WhatsApp is also currently testing a Dark Mode in an early Alpha build. The new mode is said to display incoming messages with a dark grey colour and the outgoing messages with a dark green tint. The keyboard will also automatically turn dark within WhatsApp when the dark mode is enabled. An earlier report, WhatsApp said that it is testing a "Recipient limit" on the delete for everyone option, which could impose a limit on the deleted message. In case the recipient does not receive the delete message request within 13 hours, 8 minutes and 16 seconds, the request will be discarded and the message won’t be deleted. One might not receive the message deletion request due to many reasons, like if the recipient's phone is switched off or doesn’t have data enabled. This new feature is currently said to be under testing and could be rolled out in future versions of the app. You can learn more about it here.