We´ve experienced the same thing. Actually, I was coming to this forum just to check if anyone else noticed the same issue.
I was playing DPS and shortly after the start I and the other DPS were killed almost instantly by the red circles (boss ability "songbirds salvo") The tank and the heal also received extremely much damage, but sometimes survived. After several tries, our tank and heal managed to kill Troya Ajak on their own by using severel defensive CDs, while we DPS were always killed.
We had the idea that maybe our damage was reflected or that her damage was related to the number of people, but couldn´t figure out the real reason for these damage spikes.
Would be helpful to know how to beat this boss in our next adventure to the SoV MFP, so thanks in advance for any advise.