Currently, if I have a plagued item with max health/focus reduction, say 20% from 100 focus. The problem is, my max focus is still 100, and capped at 80. So gems that rely on focus/HP being full never work, because my focus is always 80/100.
Please change the actual max, and not simply capping HP/focus gain.
This sounds more like a bug
It has always worked this way. “At low health” and “at low focus” builds rely on this to function.
In that case the wording shouldn’t be that it lowers max health or fp, but that it reserves health or fp.
I agree with you, but it’s also true that the UI isn’t clear at all. The part of the health/focus that is “locked” should be indicated somehow.
For example like this:
Instead of being like this:
I agree. If it’s meant to be a “reserve life/fp” then that part should look different than “missing life”
“Missing” ≠“Reserved”
I still believe max health/focus reduction should reduce the actual max, not reserve. If they intend for it to not work that way, then the wording should definitely change, and makes it so that gems that relies on full health/focus still work.
You may argue that that’s how low health builds are based on, precisely because this debuff is wrongly implemented. Keeping your health low should be a constant effort, making you think twice about life steal. But this debuff makes this process effortless, and you can still lifesteal because your health is capped at always a low percent.
If they intend for it to work the way it is, it makes it so that gems that rely on low health/focus still work.
You may argue that the wording should change or that its effortless, precisiely because low health builds work so well as currently implimented. Not having the wrong enchantments should be a constant effort, making you think twice which ones you choose.
You can just flip the coin here… 
I do get your point, but if we look at other games, reducing max something straight up reduces the max health. If the debuff caps the health, it should explicitly say “Maximum recoverable health reduced to 80%.” So players clearly understand: “Oh, these gems that require my health/focus to be full won’t work because of this debuff!”
At least the wording is confusing and should be changed.
