It seems to vary pretty wildly. When I’m tanking, I never get deleted, but it can get extremely spicy. I’ve seen other tanks who were just getting annihilated, like two-shot, even on small-ish pulls, and others still who were basically invulnerable.
Clearly something odd is going on scaling-wise. Even at 80 I take massively more damage in Timewalking than a Normal or even Heroic dungeon, but it’s more like enough to make sweat, not kill me. I feel like if I went in with a lower-level DH or something I might just get insta-pop’d.