Cryptkeeper Portal Bug?

I can't fully tell if this is a bug or intentional with the Cryptkeeper Portal.

I'm not 100% sure if there are more steps to reproduce, but if you open a portal, return to hideout, then re-enter the map and reopen the portal again; some of the portal's components don't get fully cleared.

Considering that opening the portal again else where on the map doesn't leave behind the effects, I'm assuming this is a bug.

Personally, if you removed the blue haze plane but left the chains and fog, and allowed only one lingering copy of the chains. This would actually be a cool effect for the portal.