Date & Time: Dec 10, 2021 11:14 EST
Frequency: Once, couldn't replicate it
Monster name: Ravana and 8 Iron Gates
Class/Level: WHM 54
Party or solo: Full Party
Area and coordinates: Thok ast Thok (Hard)

I noticed it a bit before the butterfly phase all the Iron Walls surrounding the arena had entered my agro list. I asked the party about it and one person said they didn't have it happen to them. I think they popped up after a Medica II cast but I couldn't recreate it when I tried.