My sister was play testing the new PS5 beta, and managed to get to 0 health while drowning, but she didn't die. I attached a picture below, sorry for the poor quality. She couldn't manage to reproduce it a second time, but I'm reporting it in case it can be reproduced.

Steps to reproduce:

1. Start a survival world in the latest preview for the PS5
2. Get your hunger down low enough so you can't regenerate naturally (this is important so you lose 1 full heart at a time)
3. Drown yourself until you reach 0 health
4. If your health bar is completely empty but you're not dead, then you've successfully reproduced the bug!

There may be other ways to reproduce the bug, but this is the only way I've seen it work so far.