Nightmare mob damage spike?

Is that intented? I was fighting in Fading Brink echo in Hardcore season and had no problems with the Harbinger attacks, but just random minion slapped me for 4.5k damage?
All resistances capped, ~3.5k armor.
https://sun9-22.userapi.com/s/v1/ig2/hVxtOUpUr_Gt3NRCnqAK2oRcyFS178urZuY-eXSEVmfcgoLHM963arCUnYxPccRCcBuBILhuBOmlmvPRZgnPoS20.jpg?quality=95&as=32x18,48x27,72x40,108x61,160x90,240x135,360x202,480x270,540x304,640x360,720x405,1080x607,1280x720,1440x810,1920x1080&from=bu&u=DSTTzd1cFWlICscxuDzZIbccG81lq-0kfHRZowVqwMA&cs=1920x0