>>714110796
That effect is called the susie_overlay in the files and despite the color on screen seeming to be red, it is actually Susie Pink (specifically #EA79C8 - which is used for Susie's silhouette in Chapter 2 and a few other minor Susie sprites).
It seems that people are off the mark thinking it has to do with Kris, Noelle, or the game. It looks to be Susie which is the cause of this, whether directly or indirectly.

>>713488417
Susie is a Pig-Creature
she has a Corkscrew tail
foreshadowed by Twisted Sword
Susie:
>... uhh, looks bad.
Ralsei:
>It's like a spiral.