About selling home mini's

Hello, yesterday i was selling a home mini code for google store.
This listing was removed and i got warned because it was a “prohibited gift card”
Is that because i list that in gift cards and not other type of listing?
If i list it again in another one lets say “other” and list it thru there, will be allowed?
Please answer because what can i sell on gameflip and what i cannot its not very clear.