Spell "Hit" VFX does not fade
The fire damage clouds emitted by the "hit" effect VFX_DestructHit (file "e/magic_hit_dst.nif")
are supposed to progressively fade.
They seem fully opaque in OpenMW.
For NPCs the visuals should be noticeably different, with fire clouds suddenly blinking out while they are still opaque.
For the player, this can block first-person view (see screens for comparison). I had trouble spotting the effect onscreen in vanilla, but I can't tell if it's simply due to the fading or if it's played lower on the body.