I've been out of the game for a while but I do seem to see more people running around mindlessly after my flash grenade. Before they usually just saw me anyways and shot me down.
It was buffed several months ago, to drain LA's jetpack energy and other stuff, but it's set to be nerfed again soon.
That is the EMP grenade not the flash grenade. Last time I saw anything done to the Flash bang it's white out time was reduced, and flash didn't go through walls. Also they changed grenades to be work on the victim's client rather than the throwers client. Though if you do land the grenade closer to the targets they are more likely to be affected.
Flash grenade increase the hipfire CoF by 25% since a few month. No clue about the blind effect, but if you seen this shield icon at the moment the grenade explode, consider to not enter in the room since at least 1 guy wear the clear vision implant (30 to 90% resistance to flash grenade).
The fuse was in fact reduced from 3 seconds to 1.5 seconds. However, lately, the hit marker was removed from the flash grenade, which I find quite annoying. Not sure if it's been fixed as I have not logged on in a while. However, changes on PTS are coming, introducing two different Flash grenades instead of the one we have now; Standard Flash grenades will have a 3 second fuse, 5 second white-out and 30% expansion of the CoF of affected targets. New Quick-det flash grenades will have a 1.5 second fuse, with a 2.5 / 3 second white-out and no CoF effect.
The same is true of the frag grenade. I hear that soft impact sound for when an enemy is caught in the blast, but the hit marker no longer appears. This has been since last patch I believe.