When you run out of air and your screen fades black, you have a few seconds before you die and have to reprint. When this happens in subnautica 1, the screen slowly returns to normal, giving it the feeling like regaining consiousness. In subnautica 2 however, this from black to normal happens almost instantly, so it doesnt really feel natural.

I noticed that too. I strongly prefer the effect from Subnautica 1 as well.

I imagine this is on the list already, but definitely agree the recovery effect from S1 would be good.
Agreed, the hud feels like a downgrade from the original

I kinda like that abrupt effect. It fits with the idea of being suddenly re-printed.

Effect does need adjustment, maye have at least some partial visibility / heavy viginetting. If you survive, have it quickly fade back, but not instant. Maybe some sort of brief recovery period after (after all you just nearly died again) while your air tank refils.
I feel that it is that way because they havent really implmemented a oxygen regen system aswell bc oxygen also just auto regens.
I think that death animations in general would be a huge plus. Like the Sand spear fishy guy grabs you, swims you away, the character does a muffled scream, and then he bites down hard and boom – Print lost.

and the air is replenished somehow too quickly

IRL, what happens when you are drowning is that you start having a tunnel vision. They could make it so when you get out of the water, the vision stays like that for a bit, around 5-10 s.

I also found it weird that its not in sub 2. They intentionally let the “bug” stay in sub 1/bz because it the feeling of almost not making it added alot.

I never played sub 1, I don’t like the idea of punishing efficient play though. When I hit air, I want to go straight back to it and like that that is how it currently is.
I hope with how popular this is that I can keep the existing recovery speed somehow.

Either way, it feels less untuitive how much time I have, before running out of air turns into reprinting

My first near-drowning experience in SN1 was so memorable for exactly this reason.
That short moment where you don’t know if you will make it or not, holding your breath, wondering what the afterlife in SN1 looks like, before the black fades out into the friendly sight of sun and sky above you. “I actually made it!”
I recall this started as a bug in SN1 that was turned into a feature because it felt “right”.
Keep in mind this only starts happening AFTER your oxygen hits zero. So, getting to air in just the nick of time (as the gauge hits zero) won’t trigger the fade to black. It’s more that you get an extra couple of seconds over and above what the gauge tells you.

I think another effect should be that once your oxygen reaches zero, you start taking damage over time - basically your health goes to zero during the grace period. Once you regain conciousness, your health remains at that reduced state, simulating hypoxia damage.
This would show you how close you actually came to dying and also be an incentive to keep up your health, because lower health = shorter grace period…
I miss the sound and cut scene from 1 and bz which was much more shocking in a good way.

The idea of having more time on fade to black make it more remarkable seems a good touch, reminds me of how i see the Death on every loop in Outer Wilds.