Both of these are from the 1980s American cartoon She-ra and they look far worse in person than in the photos I snapped. Last time I had checked up on them was a couple months ago during another rebagging session and they were both pristine -- no warping, discoloration, spots etc. I didn't notice then any of the vinegar smell that is now suffocating the room either.
The cels also looked better in their half-liquified state as once I pulled the layers free of the cel bags, the acetate clouded over and curled up with parts of it looking as if its eaten away entirely. The paint itself still looks pretty good once it dried out again (too bad it requires an an actual cel to display said paint).
I went around sniffing and rebagging all my other cels to find another She-ra cel also distinctly smelling of vinegar (somewhat oddly, it's coming from the layer with correction lines not the ones with actual paint) and yet another She-ra cel whose sides have started warping. All of these cels were from separate celbooks, so it really looks like a problem with that series, so She-ra is now being quarantined to its own celbook.
On one hand, its good that these are not from one of my more expensive series. On the other hand this is completely horrifying those were my best cels of Swiftwind and the Unicorn King.

In conclusion She-ra collectors... eyeball those cels good.