I'm talking about a mention even back in s1 when visiting the doctor; just a little vague forshadowing of the possiblity Nezuko's basic rules could be different to make the fake out seem less manipulative.
Every demon dies in the sun. Nezuko looks like she is dying in the sun. Surprise; it doesn't work on her! Inconsistency in core mechanics when there is no foreshadowing or attempt at it makes what could be powerful moments arbitrary and... unsatisfying. Nezuko 'dying' isn't what's important in that scene; it's that both of them thought she would die and the sacrificial choice was made anyway. Simply cutting to a perfectly fine Nezuko next scene with no groundwork is akin to a 'psyche'! Cutting heads and sunlight are the two constants. Uppers bend the head rule to help distinguish them; fine. Breaking the sun rule should not have been done so lightly is my beef. I like the focus of objective it adds to the story, but that doesn't excuse the writing from feeling sloppy.