Im talking per-content.
EX raid / dungeon / whatever = Y and Z colors, on all abilities and environment.
Purple / Pink / Blue; Almost entire raid.
Purple / Pink / Beige/brown; Nexus ? / ??
Why are all abilities the same colors everywhere?
It makes things unnecessary annoying to spot, and feels like a design flaw.
because content will be harder if there’s billions of flash arts so you can’t see your own toon. 
blizzard needs to add a way to remove spell flash arts from the game so we can go back to the roots again.
They added option to hide “non essential” spell effects. I think it was in graphics setting.
If the screen is already overloaded with bazillion spell effects, having everything show in different colors does not make things easier to visually parse. Example: Sprocketmonger from last season.
I think in this raid, things are relatively easy to see because there aren’t quite so many overlapping ground effects like in the past raids. At least on most bosses.
On last boss, last phase, a lot of the purple colors are basically identical though and could use more differentiation: protective orb, black hole orb, explosion point, and then explosion blast wave. You basically need to look at video guides before heading into such raids to lean what you need to be looking for, because in the middle of a stressful fight, it’s hard to mentally pick up those small details.
There is a right way to implement it, and a wrong way.
Flashing = Bad, no more to add there.
Having a purple background with a purple puddle you gotta dodge is just poor design.
I haven’t said we need more flashing, I have said we need clearer view.
Doesn’t work -
brand big light beam still clutter my screen. And halo and what nots still in the way to see the things.