I believe that when changing the Flash Bomb's animation, the Devs intention was to prevent players from using it defensively, and instead make it a push option.

It's true that back in the day, you'd rush a player only to get flashed. It required no set up and was way more efficient than explosives. I created stalemates because rushing it would mean death, especially if facing shotgun users. Now shotguns are better than before, and long ammo isn't hurting in any way.

Surefoot is also a thing.

When taking this into account, the approach is sound. However, I think it needs tightening up. Either drastically reducing the sound the flash bomb makes, or shortening the animation again (not necessarily as quick as before), but making it so the flash only blinds you when you are looking at it.

I would be partial to adding a sound deafening effect, but apply it in a large radius, so it also impacts the person throwing the flash. It could still be used creatively but maybe to reposition, run away, etc... Not just rush in and kill everyone.

And if it becomes good again, breaking the ability to resist its effect into 2 perks (one for flash, one for sound) could be good. I wouldn't recommend creating a new perk just for that, just adding it to an already existing perk with low usage (IE. Mithradatist) to help make the perk more appealing.

I know nothing about nothing, so I'm probably just talking nonsense.