In the game chat, there's a red envelope button that seems to let you send diamonds to other players...

In the game chat, there's a red envelope button that seems to let you send diamonds to other players. When I click on it, it says I need more "Last Shelter loot items". It says I can get those by "purchasing packages".

I can't find anything in the store labelled as loot items. I'm also not sure what packages it is referring to. Has this function been discontinued?