Ok hear me out first. Yes, I know that she is the face of the franchise and that she is the queen of fake out deaths. But I feel more so with this patch than others that she could be throwing actual death flags this time.
My first point is she's finally getting character development. The 2nd one and probably the weakest is well she's female character that's finally getting character development.
One thing I noticed her do a lot in this patch is the hand to heart emote. Which sure the devs could just be showing it off cause we finally are able to use it once you get to level 5 in the current pvp season. You could also argue that she could just be doing that as a sign of excitement at the aspect of figuring out no death involved shard travel. Yet why does she look forlorn if not remorseful whenever she does it?
She also seems to become easily weakened. We see her slightly winded after completing the warding spell. Now we don't see if Urianger was winded or not. Yet since coming back from the first he also hasn't shown any signs of being in need of some recovery. This isn't the only time post 6.0 that we have seen Y'shtola needing some form of recovery. She was also a little winded after she gave Zero some of her aether. I don't remember if there was a person between Y'shtola and Varshahn's offer of aether that got interrupted or not. Yet during our 1st trip into the 13th and post aether giving she does make a comment about how low she is before we come to the decision of bringing an unconscious Zero with us.
Now I also know that part of the reason why she and Urianger didn't help with putting up the wards to the Crystal Tower was to show that they were given outfits and weapons that were exactly like the ones they wore while on the first. Yet we have Krile who wanders over looking and sounding she could fall asleep from exhaustion at any second from helping with said seals. Course we don't know how long that took or if she helped out with it after a round of healing magics before hand. But if what Alisaie says at the start of that cutscene is to be believed they all should have felt as fit as a fiddle. Or strong enough to participate in the lv 47 fate that had just spawned.