what a prologue is to me is writing the beginning, maybe explaining some of the goings on, so that readers aren't confused. Theres also a secondary way, write a prologue of a future event that won't be covered in the book itself. Imma make my own kinda demonstration, this doesn't have anything to do with what you may be writing its just to kinda explain what i mean. Maybe one of your main characters aquaintences are part of the badguy group, maybe just v a g u e l y point to that in the prologue, like lets say they have black, messy hair and are male, maybe something like, "A black haired man stepped into the room, and began to speak to so-and-so or whatever lmao" you would be slightly, but vaguely, pointing towards the characters aquaintence being in the ranks of the supposed badguy sorry if this didn't help, i hope it was okay, tho