In my recent experience in the overworld, while wearing all iron armor, a shield, and being crouched, I take random suffocation damage when above Y level 255. At least I assume that is the case judging by what comes up on my screen. I see the air bubbles pop up for a split second above my hunger meter while taking the damage. They are all small and not the full air bubbles. The whole bubble bar shows up like this and goes away quickly after the damage occurs. Sometimes it happens only once, but other times it persists until you die. Whether you stand up or not doesn't matter if it decides to keep going. Not even falling all the way to ground level solves the problem. It seems as though it occurs more often while crouched, but I have had this to happen on rare occasions while not being crouched. I have tried taking off all armor, removing my entire inventory, and nothing seems to remedy this problem. It is rather annoying, and I hope that it is something that can be fixed rather easily. Thank you so much for your time, and I hope you can get this sorted out. Much appreciated.