It's not possible for you to have that without being the initiator to it, but with such experience once it is confirmed that your coins were still intact with the same amount then you don't need to worry it's just been converted, another move you can make is to contact the support channel for further complaints if needs be and it may also be as a result of updates, then I think that should be communicated to users.
Just a clarification to this. There was no bug. It was my mistake. Sometimes I claimed those free boxes. I think I clicked a game link that always shows after claiming a box. Then I thought I changed my currency, I ended up using my whole BUSD in a single game. I assume the BFGs were cashback. And I didn't noticed that we still need to click a particular game to show my game history. I thought every past games are shown right away by default. All is good then.