While playing in Auridon with a champion-level 350 player, I joined in a dolmen attack with two other players. Usually, I don't have much trouble with dolmen battles, but this evening, I was getting hit very hard and not doing much damage despite my high-level equipment that was in full repair, and my summoned daedra were dying almost instantly, including Greater Storm Atronachs. Also, I died twice and despite having 168 full Grand Soul Gems, I was not able to revive on the spot and had to revive at a wayshrine. I don't know if either if these issues were intentional changes or bugs.

Before and after the dolmen battle, I was having no trouble with other garden-variety critters, so the leveling issue seemed to purely be a dolmen thing.