WA is showing big icon with Mythic's Dancing Fever stacks if you have debuff. Text above is checking if anyone in the raid is below 30% HP - if there's someone below it's showing his HP with "stop" text.
If you want to see the low % announcement only if it's on you go to "low %" text aura settings -> Trigger -> Trigger 2 -> Unit -> change "Multi-target" to "Player".