Unknown Locations in Toussaint (The Witcher 3: Wild Hunt)

In the upper left corner of the Toussaint map there is a place with 2 questions with the same location (unknown places). There are drowners. When you go there, they let you pass only 1 question (actually, by killing utopians), and the second one remains a question. I don't know if this is a bug or the second one is deep underground and I can't find it. In short, I need help with how to find this unknown place or explain what this bug is and what to do about it