Player Actual Level v Quest Level and Anchor Mob Level.

thilog

I've come to the conclusion, that if a Quest is level 15 and you try to do it at lv 28, you actually take more damage, that if you were level 15.

This would explain why, I've found it more difficult to complete solo missions that were a lower level than I am, yet easier to complete missions that were higher level.

It's like you get a penalty for being higher and a boost for being lower.

I've been trying to do some of the lower story quests, to get them up to my level, but it's been rough going. To impossible to complete.

I've also noticed the nerf/buff is true for anchor mobs, I tried to help a small group near a stonefalls ancher, the mobs were level 12 2-3 of them took me to 50% health in the time it took me to kill one of them. When in fact, a lv12 normal mob, does almost no damage to me at all.

If I'm right in all of this, it means that I will not be able to complete any of the story or guild mage/fight questlines.

zaria

Dark anchors is leveled to the number of players to some degree.

Quests are not, it might be that you are less careful fighting low level mob, no buff
food and just walking in fighting instead of pulling one and one enemy.

Note that you level up linear in ESO, not exponential as in WOW so an pack of enemies 10 levels below you can easy kill you while you could solo dungeons 10 level below your level in wow.