A Forest of False Idols prophecy

I entered Kaom's dream wearing a corrupted Araku Tiki and defeated the Torchoak Grove - The amulet upgraded to an Ngamahu Tiki (corrupted), yet I still have the prophecy (a full day later). It seems an infinitely repeatable prophecy given the player wears a corrupted amulet each time.

In the past you couldn't upgrade a corrupted or alt art version of an item. I think the bug is that the amulet got upgraded in the first place.