I have a Forum Giftbox but the only options are to delete it or to put it in my vault. What is the purpose of this? Is it broken?

For now there is nothing you can do with it other than store it somewhere.

In the past there was a "pool" of items found in the box. Once the giftbox event was over, that pool was emptied, so opening it (if that option were available) would waste it and give you nothing.

They may have future giftbox events, in which case the option to open it will return and something will be inside it.

Up to you if you want to hang on to it in hopes it will one day be openable...or just a waste of space.

Stuff inside, in the past, has varied from common junk, to cash shop items.

thank you for all the info!