It is known that in order to send messages in the form of "gift packages", you can only do so via the Facebook Messenger application. Meanwhile, the "gift" feature is available on both the app version and the desktop version. Right now, if you still don't see "heart" appear in your Facebook Messenger application, close this application completely (both in the background) and restart it.
Previously, Facebook Messenger also had a lot of interesting changes to attract more attention of young users such as allowing to change the color of chat frames or changing the nickname.