Forbidden Zone meets Badass Decay (was Conveniently Less Forbidden Zone)
Harry Potter: We need somewhere where we can practice spells.
Ginny Weasley: How about the Shrieking Shack?
Harry Potter: No, that's too small...The first time this place was mentioned, all the more educated secondary characters gasped. It could be an Eldritch Location, a Dark World, an Ominous Floating Castle, you name it. The important thing is that anyone who enters this place is never seen again. It is most definitely a Forbidden Zone. Until the first time our protagonist is forced to enter, that is. Not only will they survive the trip, but they may make several more throughout the series' run. This place that used to be the most terrifying spot anyone could think of is suddenly just an unusual creepy location like any other, or even a totally normal place where the characters will go for whatever reason strikes them at the moment. Note that this is in no part due to the protagonist's involvement there, the place just simply stops being a Forbidden Zone for no reason. Over time, the place will become a convenient spot to start the more "mysterious" story arcs. It's not uncommon for the "nobody ever comes out!" from earlier in the series to become "Sometimes scary people and monsters come out, but we can totally handle that." And of course, the protagonists and even minor characters are going to visit the Forbidden Hangout many, many times before the story's over, often for completely arbitrary reasons. It becomes just another place, where ordinary and not-so-ordinary things happen every day. A key aspect of this is that the Forbidden Hangout is something that has to happen for no apparent reason. The characters enter, then leave, and for no real reason the Forbidden Zone is suddenly... not so forbidden. Even though they did nothing to change it. If the place becomes less scary or dangerous due to the protagonists' actions, it's just a normal place now, and belongs in the regular Forbidden Zone page. Characters may also be introduced who live in the Conveniently Less Forbidden Zone, always after it becomes this. Also, for some reason this happens more frequently to scary forests than anywhere else.