Na
Nah it was always dark since chapter 1 by various of those reasons:
- the dark past mini flash back in every chapter (including that since the start she explain what happened to her, the town and her family)
- the stalking vigilance of new characters when the snake lady feel suspicious movements related to our lovely trap
- the really explicit creepy warnings with explanations of what will happen (yeah she explain what will happen if you do the same thing the influencer do, since chapter before)
- the ghost in the birthday before the snake lady came, the entire scene when they came to the snake lady secret house in the underworld
I think there's a sort of deceptive thing going on where you see the two kids messing around all the time unscathed and the priestess who can't see Dara and figure that either the mountain/surrounding areas are relatively safe now and the shrine isn't really doing anything and/or the kids are extremely lucky.
When really it's probably more that:
A. The kids' instincts about whether a spirit/situation is safe are very good so they're comfortable messing around when they don't feel like something's up.
B. Dara is both safe and one of if not the strongest thing in the area, and we're usually following her around. So it's not just, "Dara won't hurt the kids," it's, "Dara won't hurt the kids and a lot of things that would are scared of her."
C. Not being able to see spirits is a huge weakness if you're trying to actively fight something like Dara's snake half but it doesn't affect your ability to conduct binding rituals. That priestess can't see Dara but she can properly set up a shrine with elements that could totally kill you.
Personally I really like when a story handles competency like this.