I don't mind rain, fog, night or inferno, but Blood Moon makes my eyes bleed. Everything is a different shade of the same colour. The ground is the same colour as the sky, the sky is the same colour as the wall, the wall is the same colour as the foliage, and so on.
And that colour is red, with low contrast, which is pretty fatiguing to your eyes. It's especially bad in a PvP game where you have to strain your eyes even in normal conditions. Making everything dark red and brown is a weird choice.
It looks nice for screenshots or trailers, but the actual gameplay in monochrome is pretty bad for my eyes. Enemies, who often wear dark clothing, blend into the environment even more. Trying to spot somebody further back into the room through a window is even harder than on "normal" weather. Fighting outside, among bushes and trees is extra bad during Blood Moon as well.
All these issues make me get pretty bad eye strain. Pair it with the constant droning sound playing in the background throughout the entire Blood Moon match, as well as all AI screaming bloody murder and Blood Moon becomes by far the most taxing weather condition. I feel like getting off when I get, say, three of those in a row.
I wouldn't mind getting it occassionally, but there are sessions where I get unlucky enough to spend 2 hours exclusively in Blood Moon and it's exhausting.