>>76737517She's envious, not jealous, anon.
She's upset that the same people that ignored her and left her to die, many of which were friends BEFORE joining Niji (like Cy Yu) are the same ones who IMMEDIATELY ran to latch onto Doki's teats for clout as soon as they possibly could while continuing to ignore Sayu.
Sayu's that uncomfortable stain on their record and a reminder that when the Doki situation happened to someone before, they all just fucking left her to die and are continuing to do so.