https://www.project1999.com/forums/s...d.php?t=337693 possibly relevant?
I didn't read it all but a dude who seemed to be doing significant testing concluded that something is wonky with dot damage if you have a target that was rooted, then breaks, then gets rooted again.
Try testing by killing like 5 giants by facetanking the whole fight to prove they die to ONLY two epic clicks as damage, without them being rooted or moving at all. Then test by pulling a giant with an epic click then rooting as it approaches. Let dot wear off, ideally without root first wearing off. Then let root wear off, dot it again, root it again as it is approaching you. If there's a bug with reduced dot damage while rooted because of this (remember that current bug with mobs appearing to run off into the distance when you root them as they approach you? hrrrrmmmmmm), two clicks won't be nearly enough to kill these giants, and the difference will be enough to not be explained by a tick or two of movement or their natural regen.
Could also test this on a lower-level mob that will die to a full-damage of one given poison dot, but will not even close to die to a fully partial (I know fully partial sounds odd) damage of the same dot.