Just replayed the Auntie Ethel section of the game - it seems like Larian has finally added in "area-based fast-travel/resting restrictions" - is this new to Patch 6? I.e. you can't fast travel nor rest now while you're in Auntie Ethel's lair. The mini-map has this red border around it to indicate it.
I love it.
It really added some serious tension to the moment because I suddenly knew I couldn't blast away endlessly with spells. I believe if someone really wanted to, they can still backtrack out of the lair and go rest. But I think that's okay because you don't want to soft-lock some players (in case they get stuck without enough resources). It's the same in old school and contemporary games (BG2, WoTR).