Is your feature request related to a problem? If so, Please describe:
Sort of. it's related but not. and it's it's own thing.

Describe the feature you'd like to see implemented:

FIRST: Dieing for a long time to get achievements or cause you're trying to save your ass or just, really REALLY don't want to go gets the heartbeat and humming sounds/effects stuck in your head. So now I'm humming a sound myself, in between bad wolf melody and vale decim before that. :V
but anyways, to tie in with my suggestion and if not, to alleviate the ears of the effects overlaid. ossibly add a way to get the sound modifications and humming sound to gradually intensify to current volume as your degrade, as a sound indicator of how grace decayed you are. Most intense when close to being critical, kinda distant and a little dizzy perhaps when just starting/soldiering on.

Speaking of which. SECOND: Being minecraft, and a game about survival what if there was a way you really could NOT change, and actually survive and stabilize yourself. which can further tie into my bug with sync and the states being kind hardwired. what if they were a little more fluid?

A form of life decay and urgency to get help... or regenerate and be fine but different all at once.

Supposed Mechanics: upon hitting zero health you get smashed into next week like a hefty sound effect/muffled sounds, fuzziness and you get a moderate amount of " decay", but instead of halving the max health and restoring that simply restore the player only by a few hearts but give them a few moments of resilience incase they're being viciously attacked so they can try to save themselves. But also now, half the the player's current hunger and saturation but disable regeneration while in what will now be called "Decaying" State.

Decaying State
What now happens is depending on how much health you've lost past a threshold (75%?) from your max your situation decays faster. If at the threshold it decays at a normal rate towards the full time required to hit critical at full
(900 seconds default at normal speed. Getting decayed removes time from this counter. Regaining it, discussed later, gives it back).

But if you get hit some more and you're down a few hearts it speeds up by a percentage. until where taking damage while empty on health - aka on deaths door - accelerates it in high burst amounts making you die far more quicker based on damage taken. You don't automatically trigger regeneration on grace death therefore, the over damage is converted into decay time reductions.

What do do instead of auto regen
because of this mechanic you can still get murderized if you're stubborn and keep trying to limp away to relative safety and survive because it won't auto regen on grace death anymore. Instead you need to trigger regeneration on your own.

Have the glowing hands be an effect that comes and goes occasionally while decaying which while it's happening you hit the regenerate button to signal that you want to regenerate before the glow time finishes or you delay. When you've signalled you're going to regen, now you enable auto regen on grace death, or simply watch yourself get enveloped in your energy color then regenerate after the glow time expires.

On the flip side, you hit the break blocks key to delay the glow and it will come back again later. If for some reason you just want to glow for cinematic effect maybe, if you've signalled the regen but want to back out, you can still slap a block to cancel back to the idle glow of the regeneration waiting to happen. Canceling regen should require the CLICK itself, not the holding of the click, as I've had a glow get canceled a few times cause I was digging which requires the left click to be held which denied it. :V

Pressing regenerate any other time when the hands don't glow on their own will trigger it's own faint hand glow. Which you can press a few more times to intensify the effect and trigger "I want to regenerate now" time window like described above by yourself at any time.

Like normal, when you regenerate if you manage to get killed through the cutscene you're dead.

If you manage to exhaust your entire grace/decay period you still go critical mode afterwards and it does accelerate like decay, but if you take a blow while on death's door you're just immediately dead, making it a bad idea to wait that long unless you're safe and looking for the achievement.

expanding on the decay stuff
The further decayed you are the more exhaustible your character is. so you apply this by taking the overall time you've decayed and applying some math to it to get a constant amount of hunger drain applied to the hunger bar.

If hunger is gone OR they have recently taken direct damage to their decay on death's door, you put the character in the movement animation state of how you do in critical: how they're clutching their front and hunched over.
But if they're both out of health and recently taking damage directly to decay, while also empty on hunger the player is fully disabled/super duper slowed and nauseated except for movement of their inventory and interaction and is rendered as basically crawling along near death.

You could also apply effects like dropping item stacks from their hand from exhaustion, taking random ticks of damage from pain shots even outside of critical, random mob sounds as paranoia sinking in etc as decay gets more advanced.

Where it all comes to a boil in critical, and then finally when fully decayed out, you're dead. As a cool side effect to the system of the mod you COULD also apply this to a "Mortal" player also, as a cool survival mechanic. Since without regens, they'd be forced to fight through it or, well, watch themselves die painfully... alone... you just remove the ability to actually trigger/focus on regenerating or any glowing at all, and make the decay be the effect to watch as it sinks in and you collapse and die in a pile.

So how do you negate this?
You keep your health high to reduce decay rate, cause more decay means faster hunger drain, no hunger means more damage which feeds into itself. So keeping on top of it means it's more fightable.

You also fill your hunger bar as much as you can with saturating foods to get that minecraftian healing factor on. When you have saturation after a certain amount of hunger tick rotations you can instead heal the player of a bit of decay and take their saturation, but not heal their health, health still won't regen normally unless you stabilize fully or use outside sources or just use a regeneration.

But if you can hook into healing taken, if you heal over max you can take a certain amount of overheal and give it directly to stabilizing the player again to further slow decay. If the player manages to beat back the entire tide of decay to it's fullest they regain their living status and they're out of the badness and they can keep going. GG you saved yourself a regen/pulled back from the brink of death by medicating yourself well enough.

blah. nevermind. xD unless you find it and really want to. too indepth and fiddly.