I'm playing a druid, and having debuffs such as magic and disease highlight on frames, despite not being able to ever cure them in Wrath/Classic and having curable only checked.. Having it on both games as a druid. Rolling back to 3.4.3 on Wrath fixes the issue.

I don't see how could this happen, can you give me a screenshot?

Here you can see that I only have zperl enabled to prevent funny business with other addons.

Here you can see a blue highlight while I'm on my druid and debuffed with immolate, with only curable clearly checked. Another commenter on the curseforge site has had a similar issue. Curiously, changing the code...

else getShow = function(Curses) return Curses.Magic or Curses.Curse or Curses.Poison or Curses.Disease

... from the ZPerl.lua file and deleting the Curses.Magic part makes this effect go away. Unfortunately, it does this for ALL characters, though. There's nearby code that tailors this to each class (eg if playerClass == "DRUID"), but somehow it doesn't seem to be working, at least for me. I tried fiddling with it a bit but didn't get anywhere.