Kaguya made that move with the help of her third eye. It's not a genjutsu, it's a real land, that's the trickery. However, if you see, it is all connected to her third eye, which is know for genjutsu because it's a sharingan, but the changes she mades via that genjutsu are real. And that's the trickery and that's why Kishi kept Kakashi and Sakura around (dunno exactly why Obito, maybe bc of his teleportation ability) becase it is a "genjutsu based" move, Kakashi being the one who discovered Sakura's genjutsu potential, Sakura being with the potential, only that it's the reverse, she dispels genjutsu, turns it into reality (ding, ding!*) and the matter at hands is that, that genjutsu based move is actually a real thing. We just don't know what's the mystery behind it.
So, now, we have the castles which are shown to us at every each change of landscape, which is connected somehow, we have Sakura, the one pointing towards the castle in the cover, we have Kakashi, like he was already waiting to go to the castle, hence he's the one stating the obvious now, collecting the data, we have Sasuke who in the cover is like far away and looks at his bow which in the manga we are shown that he was transported into a new dimension and then we have Naruto and Sakura... Sakura the one pointing towards the castle, like I said, knowing like there's something in that castle they need to take care of meaning, she will be involved in a pivotal role in this whole Kaguya matter given she has been asking about her ever since Kaguya was brought in the manga, like more into it (the Madara case) and Naruto, who is one of the pieces to that castle's trip (idk exactly how to say it).
Kishi gave us a hint in that cover and the manga is atm exactly in the situation of that cover: Kakashi and Sakura are ready to go to that castle (so to speak), Naruto knows he's on his own but oh well, he's around, like kinda he remained now in the manga, Sasuke is further away from them all admiring his bow, like he is in the manga now, apart from them and we have those castles, which definitely mean something, cause we've seen them whenever the landscape changes... And the trick is in Kaguya's third eye "power"(?) which is/would be a genjutsu based move, only that it's a "real" move, know what I mean?
And like in the cover, the ones interested of that castle, are none than Sakura and Kakashi... and lately we've seen them analyzing a lot the situation (LOL! @ Sasuke, he's gonna have his ass saved by Kakashi and Sakura, I am sure of it, you know Sasuke, the guys who you called pretty much useless because even if they analyze, they can't do nothing; oh well, guess what, you're gonna get a surprise and have your ass saved by these "useless" people with guess what... their analyzing prowess!) which means we're in for a big deal.
The only unknown problem here, the X is in Kaguya's third eye and those castles and their change of environment - and that's where Kakashi and Sakura will help. They'll find out what about these changes, whose jutsu is this - to quote a genius in life. :)