@ElMariachiPlease, my shot might be long but I'm not contradicting myself...
I mean that the plugsuit that was precariously amended sometime between 2.0 and Q might be originally Soryu's; who, as "another possibility" pertaining to another continuity (
i.e. a functional angel here, somewhat like Shinji in the RE-TAKE doujin), invaded the Rebuild continuity as the so called "Bardiel" event during 2.0. I'm supposing that Shikinami, together with her test suit, morphed at some degree into Soryu/"Bardiel" together with her old torn off plugsuit as well.
Why would she use precisely that plugsuit again after all those years, during the beginning of Q? probably as some sort of charm or significant item during Unit-1's retrieval, for she might finally meet Shinji again not just since 2.0 as Shikinami but also since EoE as Soryu.
Also, there is the already well known weird face that comes with Bardiel, behind the cross shaped blue light:
If I'm not that nuts myself, this girly thing could be Soryu Asuka's "soul".
Significantly enough, there is this quote about the extended scene about the Bardiel incident on the storyboard (taken from
here):
The most shocking scene at the end was not featured in the movie. Inside the Eva-03, the angel takes Asuka's face and says in Kaworu's voice that "a happy Asuka[?] [that] is not like you", then Asuka says that her happy self is scary and tries to put her usual face back.
It's a frail theory, I know, but it caught my eye and wanted to entertain the idea.