Imperial gardens purple map spot

[BirdFeeder]

On the map, theres a purple spot showing *below* a floating island. There doesnt seem to be any walkway or path beneath the island, its just visible there if you pan the map in a certain way. Viewing the island from different angles doesnt show anything special either, and theres nothing to shoot or destroy. Is this some kind of secret or just a bug?...

[deadshooter]

can we see a screenshot?

[Arsenik1001]

I think its a bug got the same problem on game released.