When I first met her in the grove in my first playthrough she had some weird vibes right off the bat, and gave me a healing potion which did not stack with my other potions.
That just tipped me off about something being wrong with it, and with her, and I felt SO smart for a while and refused to use it.
Turns out a bit later that items not stacking correctly is just a problem in general, and that potion was perfectly fine.
I would have loved if little clues like that meant something a bit more often. Making players find little things that uncover a bigger mystery is great and heavily underused these days.