So she can see the thread from ch.1 as well now, very interesting. It's really hard to imagine Dew is so face blind that a partial veil would stop her from at least recognizing Jiang Yang's very unique eyes, but she seems to genuinely not see a resemblance. I'm thinking given the modern office layout, that space belongs to the "author/designer Jiang Yang" before getting transmigrated, more of a representation of an authors position as the "fate weaver" of the stories they create. Reincarnated Jiang Yang might want to save Dew, but the version of her that effectively exists as a god, who created the world and knows the future, is "programmed" to stop events from deviating, including the mutual deaths of the two FLs.
The closest comparison I can think of is Ei/Raiden Shogun from Genshin, and how Ei could experience things that made her want to go against the version of her that was programmed to keep things the same for eternity.
And this has bothered me for a few chapters, but I can't tell if calling it a "mana flow" issue was an intentional decision by the author to clue Dew in on Yang's identity, because I'm confused why a cultivator seeing the literal symptoms of Qi Deviation would call it anything but that otherwise.