Artificial Difficulty

[Reynhart]

I find it hard to call real difficulty if they telegraph it with a giant red outline on the floor and give you time to get out of it.

It's a delicate balance. If the attack cannot kill you by itself, and is only targeted at you, ok, you don't need to telegrah it.
If the attack as a specific radius that you can't really guess, not telegraphing it is a step toward fake difficulty.
If the attack can one-shot you, no telegraphing it is totally fake difficulty.

And any mechanic where you absolutely need to die at least once to learn is also fake difficulty.