What gameplay feature is this bug affecting?
Backgrounds

What's the issue? Please include any error messages you receive and as much detail as possible.
When I accidentally offered a background (as part of a trade) that was already on a lion, after the trade was cancelled the background shows as nothing and is not removable. When I tried to remove the background, it told me 'the item isn't equipped to this lion'. (Also, not sure if this was an art bug or not)

Any links relating to this bug? For example, if a particular lion is bugging, what is the link to that lion?
https://www.lioden.com/lion.php?id=794132410823

Any screenshots you can provide us with?
https://imgur.com/8SG7X97 [lion]

https://imgur.com/XGoNBJO [background still showing as equipped]

Please provide us with step by step explanation how this bug happened so we can attempt to replicate it. If it's complex, please include screenshots where possible:
Equip a background (or specifically Dark Forest, I'm not sure) onto a lion and then offer the background in a trade. Then, have the trade get cancelled and attempt to remove the background from the lion/just open the lion's page.