ZEMs were in from the start. But the insane bonuses on newb dungeon ZEMs was added during PoP when they added the low level cleric rez spells etc.
I've done all the digging.
In era sources from a ShowEQ dev that the max ZEM was 100 pre-Luclin, explicit references to Crushbone and Najena ZEMs being 80, and so on.
We are playing with PoP ZEMs and this should change.
https://www.project1999.com/forums/s...d.php?t=343193