So I encountered this while playing...
It was a normal game against a Spirit in Coal Tower, and suddenly I spotted a Pustula Flower inside a T+L next to shack. I was shocked, becase there was no offering for it to appear (and outside Halloween it can't be offered). Sorry I didn't take a screenshot, but this is how it looked like. What do you guys think happened?

Comments
Dw its just the entity having nostalgia where survivors didn't bully killers
Good old times
I’m pretty sure there’s a Rift archive challenge that spawns one. If the player hasn’t completed the challenge to this day, they can make it still appear.
It's an old tome challenge. When selected, it'll spawn a pustula.
Oh, okay, thank you very much